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.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;

public class Main {

    public static void main(String[] args) {
        Problems problems = new Problems();
        problems.solve();
    }
}

class Problems {

    Parser parser = new Parser();

    void solve() {
        int t = 1;
        for (int i = 0; i < t; i++) {
            Problem problem = new Problem();
            problem.solve();
        }
    }

    class Problem {

        static final int mod = 1_000_000_007;

        void solve() {
            int n = parser.parseInt();
            int m = parser.parseInt();

            int[][] dp = new int[1029][29];
            for(int i = 0; i < dp.length; i++) {
                Arrays.fill(dp[i], -1);
            }

            System.out.println(get(dp, n + 2 * m - 1, 2 * m));
        }

        int get(int[][] dp, int n, int m) {
            if(n == m || m == 0) {
                return 1;
            }

            if(dp[n][m] != -1) {
                return dp[n][m];
            }

            return dp[n][m] = (get(dp, n - 1, m) + get(dp, n - 1, m - 1)) % mod;
        }
    }
}

class Parser {
    private final Iterator<String> stringIterator;
    private final Deque<String> inputs;

    Parser() {
        this(System.in);
    }

    Parser(InputStream in) {
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        stringIterator = br.lines().iterator();
        inputs = new ArrayDeque<>();
    }

    void fill() {
        while (inputs.isEmpty()) {
            if (!stringIterator.hasNext()) throw new NoSuchElementException();
            inputs.addAll(Arrays.asList(stringIterator.next().split(" ")));
            while (!inputs.isEmpty() && inputs.getFirst().isEmpty()) {
                inputs.removeFirst();
            }
        }
    }

    Integer parseInt() {
        fill();
        if (!inputs.isEmpty()) {
            return Integer.parseInt(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    Long parseLong() {
        fill();
        if (!inputs.isEmpty()) {
            return Long.parseLong(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    Double parseDouble() {
        fill();
        if (!inputs.isEmpty()) {
            return Double.parseDouble(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    String parseString() {
        fill();
        return inputs.removeFirst();
    }
}