import java.util.*;

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int kk = sc.nextInt();
        int[][] dp = new int[n][kk + 1];
        dp[0][0] = 1;
        for (int i = 1; i < n; i++) {
            for (int j = 0; j <= i; j++) {
                for (int k = 0; j + k <= kk; k++) {
                    dp[i][j + k] += dp[i - 1][k];
                    dp[i][j + k] %= MOD;
                }
            }
        }
        int sum = 0;
        for (int x : dp[n - 1]) {
            sum += x;
            sum %= MOD;
        }
        System.out.println(sum);
    }
}