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: import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  import static java.lang.Math.max;
  import static java.lang.System.*;
  import static java.util.Arrays.sort;
  import static java.util.Collections.replaceAll;
  import static java.util.Collections.reverseOrder;
  
  public class C {
      public static final boolean LOCAL = System.getProperty("ONLINE_JUDGE") == null;
      // public static final boolean LOCAL = System.getProperty("LOCAL")!=null;
      public static final String ANSI_RED = "\u001B[31m";
      public static final String ANSI_RESET = "\u001B[0m";
      static final int M = (int) 1e9 + 7;
      static final long MM = (long) M * M;
      static final int MAX = Integer.MAX_VALUE;
      static final int MIN = Integer.MIN_VALUE;
      static final int SIZE = (int) 1e9 * 2;
      static ArrayList<Integer> primes = new ArrayList<>();
      //static Scanner sc = new Scanner(System.in);
      static FastReader sc = new FastReader();
      static long startTime;
      static long endTime;
      static boolean[] prime;
      static int[] visited;
      static ArrayList<ArrayList<Integer>> graph;
      static ArrayList<Integer> dfs;
      static boolean isCyclic = false;
  
      public static int swap(int... args) {
          return args[0];
      }
  
      public static void main(String[] args) throws IOException {
          do {
              startTime = currentTimeMillis();
              //setOut(new PrintStream("output"));
              //setIn(new FileInputStream("input"));
           // int T = sc.nextInt();while (T-- != 0)
              {
                  solve();
  
              }
              endTime = currentTimeMillis();
              long duration = endTime - startTime;
              //out.println(duration);
              if (false) {
                  out.println(max(3, 2));
                  Integer[] ARRAY = new Integer[2];
                  ArrayList<Integer> LIST = new ArrayList<>();
                  LIST.add(2);
                  // sort(LIST, reverseOrder());
                  LIST.sort(reverseOrder());
                  sort(ARRAY, reverseOrder());
                  out.println(LIST + " " + Arrays.toString(ARRAY));
              }
          } while (false);
      }
  
      static long nCr(int n, int r) {
          return factorial(n) / (factorial(r) *
                  factorial(n - r));
      }
  
      public static void solve() throws IOException {
  /////////////////////////////////////////////////////////////////////
          int n =sc.nextInt(),m=sc.nextInt();
          PrintWriter out = new PrintWriter(System.out);
          char [] [] grid = new char[n][m];
          int [] col = new int[m+2];
          for (int i = 0; i < n; i++) {
             grid[i] = sc.next().toCharArray();
          }
          int [] cum = new int[m+2];
          for (int i = 1; i < n; i++) {
              for (int j = 1; j < m; j++) {
                  if(grid[i-1][j]=='X'&&grid[i][j-1]=='X'){
                      col[j] = 1;
                  }
              }
          }
          for (int i = 1; i < m+2; i++) {
              cum[i] = cum[i-1]+col[i];
          }
          int q =sc.nextInt();
          for (int i = 0; i < q; i++) {
              int x1 = sc.nextInt(),x2 =sc.nextInt();
              x2--;x1--;
              if(cum[x2]-cum[x1]==0){
                out.println("Yes");
              }
              else
              out.println("No");
          }
          out.close();
  ///////////////////////////////////////////////////////////////////////
  
      }
  
      static void dfs(int src) {
          visited[src] = 1;
          for (Integer integer : graph.get(src)) {
              if (visited[integer] != 1) {
                  dfs(integer);
              }
          }
          dfs.add(src);
  
      }
  
      static void detectCycle(int src) {
          visited[src] = 2;
          for (Integer integer : graph.get(src)) {
              if (visited[integer] == 0) {
                  detectCycle(integer);
              } else if (visited[integer] == 2) {
                  isCyclic = true;
                  return;
              }
  
          }
          visited[src] = 1;
      }
  
      static <Array, Target> int count(Array[] array, Target target) {
          int cn = 0;
          for (Array value : array) {
              if (value.equals(target)) cn++;
          }
          return cn;
      }
  
      static int count(String string, char target) {
          int cn = 0;
          for (int i = 0; i < string.length(); i++) {
              if (string.charAt(i) == target) cn++;
          }
          return cn;
      }
  
      static <Array> void revArray(Array[] arr) {
          int n = arr.length;
          for (int i = 0; i < n / 2; i++) {
              Array temp = arr[i];
              arr[i] = arr[n - i - 1];
              arr[n - i - 1] = temp;
          }
  
      }
  
      static <Array> void printArray(Array[] arr) {
          int n = arr.length;
          for (Array array : arr) out.print(array + " ");
          out.println();
      }
  
      static void yes() {
          out.println("YES");
      }
  
      static void no() {
          out.println("NO");
      }
  
      public static boolean isPal(String s) {
          StringBuilder stringBuilder = new StringBuilder(s);
          return s.equals(stringBuilder.reverse().toString());
      }
  
      public static int lowerBound(Integer[] array, int length, int value) {
          int low = -1;
          int hi = length;
          while (low + 1 < hi) {
              int mid = (low + hi) / 2;
              if (array[mid] <= value) {
                  low = mid;
              } else {
                  hi = mid;
              }
          }
          return low;
      }
  
      public static int upperBound(Integer[] array, int length, int value) {
          int low = -1;
          int hi = length;
          while (low + 1 < hi) {
              int mid = (low + hi) >> 1;
              if (array[mid] >= value) {
                  hi = mid;
              } else low = mid;
          }
          return hi;
      }
  
      public static int binarySearch(Integer[] arr, int length, int value) {
          int low = 0;
          int hi = length - 1;
          int ans = -1;
          while (low <= hi) {
              int mid = (low + hi) >> 1;
              if (arr[mid] > value) {
                  hi = mid - 1;
              } else if (arr[mid] < value) {
                  low = mid + 1;
              } else {
                  ans = mid;
                  break;
              }
          }
          return ans;
      }
  
      public static int gcd(int a, int b) {
          return b == 0 ? a : gcd(b, a % b);
      }
  
      public static int lcm(int a, int b) {
          return a / gcd(a, b) * b;
      }
  
      public static int countDivs(int n) {
          int cn = 0;
          int sqr = (int) Math.sqrt(n);
          for (int i = 1; i <= sqr; ++i) {
              if (n % i == 0) {
                  ++cn;
              }
          }
          cn *= 2;
          if (sqr * sqr == n) cn--;
          return cn;
      }
  
      static void prime(int x) {
          //sieve algorithm. nlog(log(n)).
          prime = new boolean[(x + 1)];
          Arrays.fill(prime, true);
          prime[0] = prime[1] = false;
          for (int i = 2; i * i <= x; i++)
              if (prime[i])
                  for (int j = i * i; j <= x; j += i)
                      prime[j] = false;
      }
  
      static boolean isEven(long x) {
          return x % 2 == 0;
      }
  
      static boolean isPrime(long x) {
          boolean flag = true;
          int sqr = (int) Math.sqrt(x);
          if (x < 2) return false;
          for (int i = 2; i <= sqr; i++) {
              if (x % i == 0) {
                  flag = false;
                  break;
              }
          }
          return flag;
      }
  
      static long factorial(long x) {
          long total = 1;
          for (int i = 2; i <= x; i++)
              total = (total * i) % M;
          return total;
      }
  
      static long power(long x, long n) {
          if (n == 0) {
              return 1;
          }
          long pow = power(x, n / 2L);
          if ((n & 1) == 1) {
              return (x * (pow) * (pow));
          }
          return (pow * pow);
      }
  
      private static <T> String ts(T t) {
          if (t == null) {
              return "null";
          }
          try {
              return ts((Iterable) t);
          } catch (ClassCastException e) {
              if (t instanceof int[]) {
                  String s = Arrays.toString((int[]) t);
                  return "{" + s.substring(1, s.length() - 1) + "}";
              } else if (t instanceof long[]) {
                  String s = Arrays.toString((long[]) t);
                  return "{" + s.substring(1, s.length() - 1) + "}";
              } else if (t instanceof char[]) {
                  String s = Arrays.toString((char[]) t);
                  return "{" + s.substring(1, s.length() - 1) + "}";
              } else if (t instanceof double[]) {
                  String s = Arrays.toString((double[]) t);
                  return "{" + s.substring(1, s.length() - 1) + "}";
              } else if (t instanceof boolean[]) {
                  String s = Arrays.toString((boolean[]) t);
                  return "{" + s.substring(1, s.length() - 1) + "}";
              }
              try {
                  return ts((Object[]) t);
              } catch (ClassCastException e1) {
                  return t.toString();
              }
          }
      }
  
      private static <T> String ts(T[] arr) {
          StringBuilder ret = new StringBuilder();
          ret.append("{");
          boolean first = true;
          for (T t : arr) {
              if (!first) {
                  ret.append(", ");
              }
              first = false;
              ret.append(ts(t));
          }
          ret.append("}");
          return ret.toString();
      }
  
      private static <T> String ts(Iterable<T> iter) {
          StringBuilder ret = new StringBuilder();
          ret.append("{");
          boolean first = true;
          for (T t : iter) {
              if (!first) {
                  ret.append(", ");
              }
              first = false;
              ret.append(ts(t));
          }
          ret.append("}");
          return ret.toString();
      }
  
      public static void dbg(Object... o) {
          if (LOCAL) {
              System.err.print("Line #" + Thread.currentThread().getStackTrace()[2].getLineNumber() + ": [");
              for (int i = 0; i < o.length; i++) {
                  if (i != 0) {
                      System.err.print(", ");
                  }
                  System.err.print(ts(o[i]));
              }
              System.err.println("]");
          }
      }
  
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new
                      InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  
      static class Pair implements Comparable<Pair> {
          private int key;
          private int value;
  
          public Pair(int key, int value) {
              this.key = key;
              this.value = value;
          }
  
          public int second() {
              return value;
          }
  
          @Override
          public int compareTo(Pair o) {
              return -Integer.compare(key, o.key);
          }
  
          @Override
          public String toString() {
              return "Pair{" + "x=" + key + ", y=" + value + '}';
          }
      }
  
  }