description: The problem statement looms below, filling you with determination.
  
  Consider a grid in which some cells are empty and some cells are filled. Call a cell in this grid exitable if, starting at that cell, you can exit the grid by moving up and left through only empty cells. This includes the cell itself, so all filled in cells are not exitable. Note that you can exit the grid from any leftmost empty cell (cell in the first column) by going left, and from any topmost empty cell (cell in the first row) by going up.
  
  Let's call a grid determinable if, given only which cells are exitable, we can exactly determine which cells are filled in and which aren't.
  
  You are given a grid a of dimensions n × m , i. e. a grid with n rows and m columns. You need to answer q queries (1 ≤ q ≤ 2 ⋅ 10^5). Each query gives two integers x_1, x_2 (1 ≤ x_1 ≤ x_2 ≤ m) and asks whether the subgrid of a consisting of the columns x_1, x_1 + 1, …, x_2 - 1, x_2 is determinable.
  
  Input
  
  The first line contains two integers n, m (1 ≤ n, m ≤ 10^6, nm ≤ 10^6) — the dimensions of the grid a.
  
  n lines follow. The y-th line contains m characters, the x-th of which is 'X' if the cell on the intersection of the the y-th row and x-th column is filled and "." if it is empty.
  
  The next line contains a single integer q (1 ≤ q ≤ 2 ⋅ 10^5) — the number of queries.
  
  q lines follow. Each line contains two integers x_1 and x_2 (1 ≤ x_1 ≤ x_2 ≤ m), representing a query asking whether the subgrid of a containing the columns x_1, x_1 + 1, …, x_2 - 1, x_2 is determinable.
  
  Output
  
  For each query, output one line containing "YES" if the subgrid specified by the query is determinable and "NO" otherwise. The output is case insensitive (so "yEs" and "No" will also be accepted).
  
  Example
  
  Input
  
  
  4 5
  ..XXX
  ...X.
  ...X.
  ...X.
  5
  1 3
  3 3
  4 5
  5 5
  1 5
  
  
  Output
  
  
  YES
  YES
  NO
  YES
  NO
  
  Note
  
  For each query of the example, the corresponding subgrid is displayed twice below: first in its input format, then with each cell marked as "E" if it is exitable and "N" otherwise.
  
  For the first query: 
      
      
        
      ..X EEN  
      ... EEE  
      ... EEE  
      ... EEE  
      
      
      
        
        
      
  
  For the second query: 
      
      
        
      X N  
      . E  
      . E  
      . E  
      
  
  Note that you can exit the grid by going left from any leftmost cell (or up from any topmost cell); you do not need to reach the top left corner cell to exit the grid.
      
      
        
        
      
  
  For the third query: 
      
      
        
      XX NN  
      X. NN  
      X. NN  
      X. NN  
      
  
  This subgrid cannot be determined only from whether each cell is exitable, because the below grid produces the above "exitability grid" as well: 
      
      
        
      XX  
      XX  
      XX  
      XX  
      
      
      
        
        
      
  
  For the fourth query: 
      
      
        
      X N  
      . E  
      . E  
      . E  
      
      
      
        
        
      
  
  For the fifth query: 
      
      
        
      ..XXX EENNN  
      ...X. EEENN  
      ...X. EEENN  
      ...X. EEENN  
      
  
  This query is simply the entire grid. It cannot be determined only from whether each cell is exitable because the below grid produces the above "exitability grid" as well: 
      
      
        
      ..XXX  
      ...XX  
      ...XX  
      ...XX  
      
solution: //package round749;
  import java.io.*;
  import java.util.*;
  
  public class C {
  	InputStream is;
  	FastWriter out;
  //	String INPUT = "3 3 XXX X.. X.. 6 1 1 2 2 3 3 1 2 2 3 1 3";
  //	String INPUT = "3 3 XXX X.X X.X 6 1 1 2 2 3 3 1 2 2 3 1 3";
  	String INPUT = "";
  
  	void solve()
  	{
  		int n = ni(), m = ni();
  		char[][] map = nm(n,m);
  
  		int[][] reachr = new int[n][m];
  		int[][] reachc = new int[n][m];
  		for(int i = 0;i < n;i++){
  			Arrays.fill(reachr[i], 99999999);
  			Arrays.fill(reachc[i], 99999999);
  		}
  		for(int i = 0;i < n;i++){
  			for(int j = 0;j < m;j++){
  				if(map[i][j] != 'X'){
  					if(i == 0){
  						reachr[i][j] = -1;
  					}else{
  						reachr[i][j] = i-1;
  						reachr[i][j] = Math.min(reachr[i][j], reachr[i-1][j]);
  						if(j-1 >= 0)reachr[i][j] = Math.min(reachr[i][j], reachr[i][j-1]);
  					}
  					if(j == 0){
  						reachc[i][j] = -1;
  					}else{
  						reachc[i][j] = j-1;
  						if(i-1 >= 0)reachc[i][j] = Math.min(reachc[i][j], reachc[i-1][j]);
  						reachc[i][j] = Math.min(reachc[i][j], reachc[i][j-1]);
  					}
  				}
  			}
  		}
  
  //		for(int[] row : reachc){
  //			tr(row);
  //		}
  
  		int[] mins = new int[m];
  		Arrays.fill(mins, 99999999);
  		LST done = new LST(m);
  		done.setRange(m);
  		for(int i = 0;i < m;i++){
  			int mx = -1;
  			for(int j = 0;j < n;j++){
  				if(map[j][i] == 'X')continue;
  				if(reachr[j][i] != -1){
  					mx = Math.max(mx, reachc[j][i]);
  				}
  			}
  			if(mx != -1){
  				for(int j = done.next(0);j != -1 && j < mx+1;j = done.next(j)){
  					done.unset(j);
  					mins[j] = i;
  				}
  			}
  		}
  
  		int[] hit = new int[m+1];
  		Arrays.fill(hit, -1);
  		hit[m] = m;
  		for(int i = 1;i < n;i++){
  			for(int j = 1;j < m;j++){
  				if(map[i][j] == 'X' && map[i-1][j] == 'X' && map[i][j-1] == 'X'){
  					hit[j-1] = j;
  				}
  			}
  		}
  		for(int i = m-1;i >= 0;i--){
  			if(hit[i] == -1)hit[i] = hit[i+1];
  		}
  
  
  		int Q = ni();
  		for(int i = 0;i < Q;i++){
  			int l = ni()-1, r = ni()-1;
  			if(Math.min(hit[l], mins[l]) <=  r){
  				out.println("NO");
  			}else{
  				out.println("YES");
  			}
  		}
  	}
  
  	public static class LST {
  		public long[][] set;
  		public int n;
  		//	public int size;
  
  		public LST(int n) {
  			this.n = n;
  			int d = 1;
  			for(int m = n;m > 1;m>>>=6, d++);
  
  			set = new long[d][];
  			for(int i = 0, m = n>>>6;i < d;i++, m>>>=6){
  				set[i] = new long[m+1];
  			}
  			//		size = 0;
  		}
  
  		// [0,r)
  		public LST setRange(int r)
  		{
  			for(int i = 0;i < set.length;i++, r=r+63>>>6){
  				for(int j = 0;j < r>>>6;j++){
  					set[i][j] = -1L;
  				}
  				if((r&63) != 0)set[i][r>>>6] |= (1L<<r)-1;
  			}
  			return this;
  		}
  
  		// [0,r)
  		public LST unsetRange(int r)
  		{
  			if(r >= 0){
  				for(int i = 0;i < set.length;i++, r=r+63>>>6){
  					for(int j = 0;j < r+63>>>6;j++){
  						set[i][j] = 0;
  					}
  					if((r&63) != 0)set[i][r>>>6] &= -(1L << r);
  				}
  			}
  			return this;
  		}
  
  		public LST set(int pos)
  		{
  			if(pos >= 0 && pos < n){
  				//			if(!get(pos))size++;
  				for(int i = 0;i < set.length;i++, pos>>>=6){
  					set[i][pos>>>6] |= 1L<<pos;
  				}
  			}
  			return this;
  		}
  
  		public LST unset(int pos)
  		{
  			if(pos >= 0 && pos < n){
  				//			if(get(pos))size--;
  				for(int i = 0;i < set.length && (i == 0 || set[i-1][pos] == 0L);i++, pos>>>=6){
  					set[i][pos>>>6] &= ~(1L<<pos);
  				}
  			}
  			return this;
  		}
  
  		public boolean get(int pos)
  		{
  			return pos >= 0 && pos < n && set[0][pos>>>6]<<~pos<0;
  		}
  
  		public LST toggle(int pos)
  		{
  			return get(pos) ? unset(pos) : set(pos);
  		}
  
  		public int prev(int pos)
  		{
  			for(int i = 0;i < set.length && pos >= 0;i++, pos>>>=6, pos--){
  				int pre = prev(set[i][pos>>>6], pos&63);
  				if(pre != -1){
  					pos = pos>>>6<<6|pre;
  					while(i > 0)pos = pos<<6|63-Long.numberOfLeadingZeros(set[--i][pos]);
  					return pos;
  				}
  			}
  			return -1;
  		}
  
  		public int next(int pos)
  		{
  			for(int i = 0;i < set.length && pos>>>6 < set[i].length;i++, pos>>>=6, pos++){
  				int nex = next(set[i][pos>>>6], pos&63);
  				if(nex != -1){
  					pos = pos>>>6<<6|nex;
  					while(i > 0)pos = pos<<6|Long.numberOfTrailingZeros(set[--i][pos]);
  					return pos;
  				}
  			}
  			return -1;
  		}
  
  		private static int prev(long set, int n)
  		{
  			long h = set<<~n;
  			if(h == 0L)return -1;
  			return -Long.numberOfLeadingZeros(h)+n;
  		}
  
  		private static int next(long set, int n)
  		{
  			long h = set>>>n;
  			if(h == 0L)return -1;
  			return Long.numberOfTrailingZeros(h)+n;
  		}
  
  		@Override
  		public String toString()
  		{
  			List<Integer> list = new ArrayList<>();
  			for(int pos = next(0);pos != -1;pos = next(pos+1)){
  				list.add(pos);
  			}
  			return list.toString();
  		}
  	}
  
  
  	void run() throws Exception
  	{
  		is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
  		out = new FastWriter(System.out);
  		
  		long s = System.currentTimeMillis();
  		solve();
  		out.flush();
  		tr(System.currentTimeMillis()-s+"ms");
  	}
  	
  	public static void main(String[] args) throws Exception { new C().run(); }
  	
  	private byte[] inbuf = new byte[1024];
  	public int lenbuf = 0, ptrbuf = 0;
  	
  	private int readByte()
  	{
  		if(lenbuf == -1)throw new InputMismatchException();
  		if(ptrbuf >= lenbuf){
  			ptrbuf = 0;
  			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
  			if(lenbuf <= 0)return -1;
  		}
  		return inbuf[ptrbuf++];
  	}
  	
  	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
  	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
  	
  	private double nd() { return Double.parseDouble(ns()); }
  	private char nc() { return (char)skip(); }
  	
  	private String ns()
  	{
  		int b = skip();
  		StringBuilder sb = new StringBuilder();
  		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
  			sb.appendCodePoint(b);
  			b = readByte();
  		}
  		return sb.toString();
  	}
  	
  	private char[] ns(int n)
  	{
  		char[] buf = new char[n];
  		int b = skip(), p = 0;
  		while(p < n && !(isSpaceChar(b))){
  			buf[p++] = (char)b;
  			b = readByte();
  		}
  		return n == p ? buf : Arrays.copyOf(buf, p);
  	}
  
  	private int[] na(int n)
  	{
  		int[] a = new int[n];
  		for(int i = 0;i < n;i++)a[i] = ni();
  		return a;
  	}
  
  	private long[] nal(int n)
  	{
  		long[] a = new long[n];
  		for(int i = 0;i < n;i++)a[i] = nl();
  		return a;
  	}
  
  	private char[][] nm(int n, int m) {
  		char[][] map = new char[n][];
  		for(int i = 0;i < n;i++)map[i] = ns(m);
  		return map;
  	}
  
  	private int[][] nmi(int n, int m) {
  		int[][] map = new int[n][];
  		for(int i = 0;i < n;i++)map[i] = na(m);
  		return map;
  	}
  
  	private int ni() { return (int)nl(); }
  
  	private long nl()
  	{
  		long num = 0;
  		int b;
  		boolean minus = false;
  		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
  		if(b == '-'){
  			minus = true;
  			b = readByte();
  		}
  
  		while(true){
  			if(b >= '0' && b <= '9'){
  				num = num * 10 + (b - '0');
  			}else{
  				return minus ? -num : num;
  			}
  			b = readByte();
  		}
  	}
  
  	public static class FastWriter
  	{
  		private static final int BUF_SIZE = 1<<13;
  		private final byte[] buf = new byte[BUF_SIZE];
  		private final OutputStream out;
  		private int ptr = 0;
  
  		private FastWriter(){out = null;}
  
  		public FastWriter(OutputStream os)
  		{
  			this.out = os;
  		}
  
  		public FastWriter(String path)
  		{
  			try {
  				this.out = new FileOutputStream(path);
  			} catch (FileNotFoundException e) {
  				throw new RuntimeException("FastWriter");
  			}
  		}
  
  		public FastWriter write(byte b)
  		{
  			buf[ptr++] = b;
  			if(ptr == BUF_SIZE)innerflush();
  			return this;
  		}
  
  		public FastWriter write(char c)
  		{
  			return write((byte)c);
  		}
  
  		public FastWriter write(char[] s)
  		{
  			for(char c : s){
  				buf[ptr++] = (byte)c;
  				if(ptr == BUF_SIZE)innerflush();
  			}
  			return this;
  		}
  
  		public FastWriter write(String s)
  		{
  			s.chars().forEach(c -> {
  				buf[ptr++] = (byte)c;
  				if(ptr == BUF_SIZE)innerflush();
  			});
  			return this;
  		}
  
  		private static int countDigits(int l) {
  			if (l >= 1000000000) return 10;
  			if (l >= 100000000) return 9;
  			if (l >= 10000000) return 8;
  			if (l >= 1000000) return 7;
  			if (l >= 100000) return 6;
  			if (l >= 10000) return 5;
  			if (l >= 1000) return 4;
  			if (l >= 100) return 3;
  			if (l >= 10) return 2;
  			return 1;
  		}
  
  		public FastWriter write(int x)
  		{
  			if(x == Integer.MIN_VALUE){
  				return write((long)x);
  			}
  			if(ptr + 12 >= BUF_SIZE)innerflush();
  			if(x < 0){
  				write((byte)'-');
  				x = -x;
  			}
  			int d = countDigits(x);
  			for(int i = ptr + d - 1;i >= ptr;i--){
  				buf[i] = (byte)('0'+x%10);
  				x /= 10;
  			}
  			ptr += d;
  			return this;
  		}
  
  		private static int countDigits(long l) {
  			if (l >= 1000000000000000000L) return 19;
  			if (l >= 100000000000000000L) return 18;
  			if (l >= 10000000000000000L) return 17;
  			if (l >= 1000000000000000L) return 16;
  			if (l >= 100000000000000L) return 15;
  			if (l >= 10000000000000L) return 14;
  			if (l >= 1000000000000L) return 13;
  			if (l >= 100000000000L) return 12;
  			if (l >= 10000000000L) return 11;
  			if (l >= 1000000000L) return 10;
  			if (l >= 100000000L) return 9;
  			if (l >= 10000000L) return 8;
  			if (l >= 1000000L) return 7;
  			if (l >= 100000L) return 6;
  			if (l >= 10000L) return 5;
  			if (l >= 1000L) return 4;
  			if (l >= 100L) return 3;
  			if (l >= 10L) return 2;
  			return 1;
  		}
  
  		public FastWriter write(long x)
  		{
  			if(x == Long.MIN_VALUE){
  				return write("" + x);
  			}
  			if(ptr + 21 >= BUF_SIZE)innerflush();
  			if(x < 0){
  				write((byte)'-');
  				x = -x;
  			}
  			int d = countDigits(x);
  			for(int i = ptr + d - 1;i >= ptr;i--){
  				buf[i] = (byte)('0'+x%10);
  				x /= 10;
  			}
  			ptr += d;
  			return this;
  		}
  
  		public FastWriter write(double x, int precision)
  		{
  			if(x < 0){
  				write('-');
  				x = -x;
  			}
  			x += Math.pow(10, -precision)/2;
  			//		if(x < 0){ x = 0; }
  			write((long)x).write(".");
  			x -= (long)x;
  			for(int i = 0;i < precision;i++){
  				x *= 10;
  				write((char)('0'+(int)x));
  				x -= (int)x;
  			}
  			return this;
  		}
  
  		public FastWriter writeln(char c){
  			return write(c).writeln();
  		}
  
  		public FastWriter writeln(int x){
  			return write(x).writeln();
  		}
  
  		public FastWriter writeln(long x){
  			return write(x).writeln();
  		}
  
  		public FastWriter writeln(double x, int precision){
  			return write(x, precision).writeln();
  		}
  
  		public FastWriter write(int... xs)
  		{
  			boolean first = true;
  			for(int x : xs) {
  				if (!first) write(' ');
  				first = false;
  				write(x);
  			}
  			return this;
  		}
  
  		public FastWriter write(long... xs)
  		{
  			boolean first = true;
  			for(long x : xs) {
  				if (!first) write(' ');
  				first = false;
  				write(x);
  			}
  			return this;
  		}
  
  		public FastWriter writeln()
  		{
  			return write((byte)'\n');
  		}
  
  		public FastWriter writeln(int... xs)
  		{
  			return write(xs).writeln();
  		}
  
  		public FastWriter writeln(long... xs)
  		{
  			return write(xs).writeln();
  		}
  
  		public FastWriter writeln(char[] line)
  		{
  			return write(line).writeln();
  		}
  
  		public FastWriter writeln(char[]... map)
  		{
  			for(char[] line : map)write(line).writeln();
  			return this;
  		}
  
  		public FastWriter writeln(String s)
  		{
  			return write(s).writeln();
  		}
  
  		private void innerflush()
  		{
  			try {
  				out.write(buf, 0, ptr);
  				ptr = 0;
  			} catch (IOException e) {
  				throw new RuntimeException("innerflush");
  			}
  		}
  
  		public void flush()
  		{
  			innerflush();
  			try {
  				out.flush();
  			} catch (IOException e) {
  				throw new RuntimeException("flush");
  			}
  		}
  
  		public FastWriter print(byte b) { return write(b); }
  		public FastWriter print(char c) { return write(c); }
  		public FastWriter print(char[] s) { return write(s); }
  		public FastWriter print(String s) { return write(s); }
  		public FastWriter print(int x) { return write(x); }
  		public FastWriter print(long x) { return write(x); }
  		public FastWriter print(double x, int precision) { return write(x, precision); }
  		public FastWriter println(char c){ return writeln(c); }
  		public FastWriter println(int x){ return writeln(x); }
  		public FastWriter println(long x){ return writeln(x); }
  		public FastWriter println(double x, int precision){ return writeln(x, precision); }
  		public FastWriter print(int... xs) { return write(xs); }
  		public FastWriter print(long... xs) { return write(xs); }
  		public FastWriter println(int... xs) { return writeln(xs); }
  		public FastWriter println(long... xs) { return writeln(xs); }
  		public FastWriter println(char[] line) { return writeln(line); }
  		public FastWriter println(char[]... map) { return writeln(map); }
  		public FastWriter println(String s) { return writeln(s); }
  		public FastWriter println() { return writeln(); }
  	}
  
  	public void trnz(int... o)
  	{
  		for(int i = 0;i < o.length;i++)if(o[i] != 0)System.out.print(i+":"+o[i]+" ");
  		System.out.println();
  	}
  
  	// print ids which are 1
  	public void trt(long... o)
  	{
  		Queue<Integer> stands = new ArrayDeque<>();
  		for(int i = 0;i < o.length;i++){
  			for(long x = o[i];x != 0;x &= x-1)stands.add(i<<6|Long.numberOfTrailingZeros(x));
  		}
  		System.out.println(stands);
  	}
  
  	public void tf(boolean... r)
  	{
  		for(boolean x : r)System.out.print(x?'#':'.');
  		System.out.println();
  	}
  
  	public void tf(boolean[]... b)
  	{
  		for(boolean[] r : b) {
  			for(boolean x : r)System.out.print(x?'#':'.');
  			System.out.println();
  		}
  		System.out.println();
  	}
  
  	public void tf(long[]... b)
  	{
  		if(INPUT.length() != 0) {
  			for (long[] r : b) {
  				for (long x : r) {
  					for (int i = 0; i < 64; i++) {
  						System.out.print(x << ~i < 0 ? '#' : '.');
  					}
  				}
  				System.out.println();
  			}
  			System.out.println();
  		}
  	}
  
  	public void tf(long... b)
  	{
  		if(INPUT.length() != 0) {
  			for (long x : b) {
  				for (int i = 0; i < 64; i++) {
  					System.out.print(x << ~i < 0 ? '#' : '.');
  				}
  			}
  			System.out.println();
  		}
  	}
  
  	private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
  	private void tr(Object... o) { if(!oj)System.out.println(Arrays.deepToString(o)); }
  }
  