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.*;
/**
  * Built using my Brain
  * Actual solution is at the bottom
  *
  * @author Lenard Hoffstader
*/

public class cfjava
{
  public static void main(String[] args)
  {
    OutputStream outputStream = System.out;
    FastReader in = new FastReader();
    PrintWriter out = new PrintWriter(outputStream);
    PROBLEM solver = new PROBLEM();
    int t=1;
    // t=in.nextInt();
    for(int i=0;i<t;i++){
      solver.solve(in, out);
    }
    out.close();
  }

  static class PROBLEM
  {
    public void solve(FastReader in,PrintWriter out)
    {
      int n=in.nextInt(),m=in.nextInt();
      long mod=(long)1e9+7;
      long dp[][]=new long[n][2*m];
      for(int i=0;i<2*m;i++)dp[0][i]=1;
      for(int i=0;i<n;i++)dp[i][0]=(i+1);
      for(int i=1;i<n;i++){
        for(int j=1;j<2*m;j++){
          dp[i][j]=(dp[i-1][j]+dp[i][j-1])%mod;
        }
      }
      out.println(dp[n-1][2*m-1]);
    }
  }
  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());}

    boolean nextBoolean(){
      if(nextInt()==1)return true;
      else return false;
    }
    // boolean nextBoolean(){return Boolean.parseBoolean(next());}

    String nextLine() 
    { 
      String str = ""; 
      try
      { 
        str = br.readLine(); 
      } 
      catch (IOException e){e.printStackTrace();} 
      return str; 
    } 
  }
}