Joisino has a bar of length N, which has M marks on it. The distance from the left end of the bar to the i-th mark is X_i.

She will place several squares on this bar. Here, the following conditions must be met:

* Only squares with integral length sides can be placed.
* Each square must be placed so that its bottom side touches the bar.
* The bar must be completely covered by squares. That is, no square may stick out of the bar, and no part of the bar may be left uncovered.
* The boundary line of two squares may not be directly above a mark.



<image>

Examples of arrangements that satisfy/violate the conditions

The beauty of an arrangement of squares is defined as the product of the areas of all the squares placed. Joisino is interested in the sum of the beauty over all possible arrangements that satisfy the conditions. Write a program to find it. Since it can be extremely large, print the sum modulo 10^9+7.

Constraints

* All input values are integers.
* 1 \leq N \leq 10^9
* 0 \leq M \leq 10^5
* 1 \leq X_1 < X_2 < ... < X_{M-1} < X_M \leq N-1

Input

Input is given from Standard Input in the following format:


N M
X_1 X_2 ... X_{M-1} X_M


Output

Print the sum of the beauty over all possible arrangements that satisfy the conditions, modulo 10^9+7.

Examples

Input

3 1
2


Output

13


Input

5 2
2 3


Output

66


Input

10 9
1 2 3 4 5 6 7 8 9


Output

100


Input

1000000000 0


Output

693316425
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Main {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	// 1 5 18 63 221 776 2725 9569
	// 776-5*63*2+5*5*5
	// 9569-63*63-5*776*2+5*5*63*3-5*5*5*5
	
	static void solve()
	{
		int n = ni(), m = ni();
		int[] x = new int[m+2];
		x[0] = 0;
		x[m+1] = n;
		for(int i = 1;i <= m;i++)x[i] = ni();
		Arrays.sort(x);
		
		int[] v = {5, 1, 0};
		int[][] M = {
				{4, mod-2, 1},
				{1, 0, 0},
				{0 ,1 ,0}
		};
		for(int i = 1;i <= m+1;i++){
			v = pow(M, v, x[i]-x[i-1]);
			long w = v[2];
			v[0] -= 5L * w % mod;
			if(v[0] < 0)v[0] += mod;
			v[1] -= w;
			if(v[1] < 0)v[1] += mod;
		}
		out.println(v[2]);
	}
	
	public static final int mod = 1000000007;
	public static final long m2 = (long)mod*mod;
	public static final long BIG = 8L*m2;
	
	// A^e*v
	public static int[] pow(int[][] A, int[] v, long e)
	{
		for(int i = 0;i < v.length;i++){
			if(v[i] >= mod)v[i] %= mod;
		}
		int[][] MUL = A;
		for(;e > 0;e>>>=1) {
			if((e&1)==1)v = mul(MUL, v);
			MUL = p2(MUL);
		}
		return v;
	}
	
	// int matrix*int vector
	public static int[] mul(int[][] A, int[] v)
	{
		int m = A.length;
		int n = v.length;
		int[] w = new int[m];
		for(int i = 0;i < m;i++){
			long sum = 0;
			for(int k = 0;k < n;k++){
				sum += (long)A[i][k] * v[k];
				if(sum >= BIG)sum -= BIG;
			}
			w[i] = (int)(sum % mod);
		}
		return w;
	}
	
	// int matrix^2 (be careful about negative value)
	public static int[][] p2(int[][] A)
	{
		int n = A.length;
		int[][] C = new int[n][n];
		for(int i = 0;i < n;i++){
			long[] sum = new long[n];
			for(int k = 0;k < n;k++){
				for(int j = 0;j < n;j++){
					sum[j] += (long)A[i][k] * A[k][j];
					if(sum[j] >= BIG)sum[j] -= BIG;
				}
			}
			for(int j = 0;j < n;j++){
				C[i][j] = (int)(sum[j] % mod);
			}
		}
		return C;
	}

	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static 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 static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
//	private static boolean isSpaceChar(int c) { return !(c >= 32 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static 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 static 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 static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, 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();
		}
	}
	
	private static 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();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}
