You are given two integers n and m. Calculate the number of pairs of arrays (a, b) such that:

  * the length of both arrays is equal to m; 
  * each element of each array is an integer between 1 and n (inclusive); 
  * a_i ≤ b_i for any index i from 1 to m; 
  * array a is sorted in non-descending order; 
  * array b is sorted in non-ascending order. 



As the result can be very large, you should print it modulo 10^9+7.

Input

The only line contains two integers n and m (1 ≤ n ≤ 1000, 1 ≤ m ≤ 10).

Output

Print one integer – the number of arrays a and b satisfying the conditions described above modulo 10^9+7.

Examples

Input


2 2


Output


5


Input


10 1


Output


55


Input


723 9


Output


157557417

Note

In the first test there are 5 suitable arrays: 

  * a = [1, 1], b = [2, 2]; 
  * a = [1, 2], b = [2, 2]; 
  * a = [2, 2], b = [2, 2]; 
  * a = [1, 1], b = [2, 1]; 
  * a = [1, 1], b = [1, 1]. 
import java.io.*;
import java.util.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

public class Main {
    public static void main(String[] args) throws IOException {
//        FastScanner in = new FastScanner(System.in);
//        PrintWriter out = new PrintWriter(System.out);
        FastScanner in = new FastScanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        int m = in.nextInt();
        long up[][] = new long[m][n];
        long down[][] = new long[m][n];
        for (int i = 0; i < n; i++) {
            up[0][i] = 1;
            down[0][i] = 1;
        }
        long mod = (long)1e9 + 7;
        for (int i = 1; i < m; i++) {
            for (int j = 0; j < n; j++) {
                for (int k = 0; k <= j; k++) {
                     up[i][j]+=up[i-1][k];
                     up[i][j]%=mod;
                }
            }
        }
        for (int i = 1; i < m; i++) {
            for (int j = 0; j < n; j++) {
                for (int k = j; k < n; k++) {
                    down[i][j]+=down[i-1][k];
                    down[i][j]%=mod;
                }
            }
        }
        long ans = 0;
        for (int i = 0; i < n; i++) {
            for (int j = i; j >= 0; j--) {
                ans+=((down[m-1][i] * up[m-1][j])%mod);
                ans%=mod;
            }
        }
        out.println(ans);
        out.close();
     }
}

class FastScanner {
    BufferedReader br;
    StringTokenizer st;

    FastScanner(File f) throws FileNotFoundException {
        br = new BufferedReader(new FileReader(f));
    }

    FastScanner(InputStream is) {
        br = new BufferedReader(new InputStreamReader(is));
    }

    String next() throws IOException {
        while (st == null || !st.hasMoreTokens())
            st = new StringTokenizer(br.readLine());
        return st.nextToken();
    }

    int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    long nextLong() throws IOException {
        return Long.parseLong(next());
    }
}