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]. 
/*

I FOLLOW THE WAY OF THE RIGHT HONOURABLE JIM KWIK,
GOD BLESS YOU SIR

1.  I AM A 'NEWBIE' IN RATING
2.  I WILL FAIL MANY TIMES, BUT I WILL NOT FAIL TO LEARN FROM FAILURE
3.  I WILL NEVER SURRENDER MY GOAL, NO MATTER HOW MUCH I FAIL
4.  I WILL PROVE MY SKILLS WHEN THE TIME COMES
5.  I WILL ALWAYS KEEP TRYING

*/








import java.util.*;
import java.io.*;
public class A  {

















    static boolean tests = false;
    static long[] fact;
    static long power(long a, long p){
        long ans = 1, temp = a;
        while (p != 0){
            if (p % 2 != 0) ans = mul(ans, temp);
            temp = mul(temp, temp);
            p /= 2;
        }
        return ans;
    }
    static long mul(long a, long b){
        return (a%mod)*(b%mod)%mod;
    }
    static long div(long a, long b){
        return a*power(b, mod-2)%mod;
    }
    static long add(long a, long b){
        return ((a%mod)+(b%mod)+mod)%mod;
    }
    static long choose(int n, int k){
        if (fact == null){
            fact = new long[2*(int)1e5+5];
            fact[0] = 1;
            for (int i = 1; i < fact.length; ++i)
                fact[i] = mul(fact[i-1], i);
        }
        return div(div(fact[n], fact[k]), fact[n-k]);
    }
    static void solve(){
       int n = in.nextInt(), m = in.nextInt();
       out.println(choose(2*m+n-1, n-1));
    }





























    static Reader in;
    static PrintWriter out;
    static int int_max = (int)1e9, mod = int_max+7;
    public static void main(String[] args){
        in = new Reader();
        out = new PrintWriter(System.out);
        int t = tests ? in.nextInt() : 1;
        while (t-- > 0) solve();
        out.close();
    }
    static class Reader{
        // Reader credited to SecondThread
        BufferedReader b;
        StringTokenizer s;
        Reader(){
            this.b = new BufferedReader(new InputStreamReader(System.in));
            this.s = new StringTokenizer("");
        }
        String next(){
            while (!s.hasMoreTokens())
                try{s = new StringTokenizer(b.readLine());
                }catch(IOException ignored){}
            return s.nextToken();
        }
        int nextInt(){return Integer.parseInt(next());}
        long nextLong(){return Long.parseLong(next());}
        double nextDouble(){return Double.parseDouble(next());}
        int[] ai(int n){
            int[] a = new int[n];
            for (int i = 0; i < n; ++i)
                a[i] = nextInt();
            return a;
        }
        long[] al(int n){
            long[] a = new long[n];
            for (int i = 0; i < n; ++i)
                a[i] = nextLong();
            return a;
        }
    }
}