bits -더블릿

#include <stdio.h>
 
typedef long long ll;
ll dp[1000][1000] = { 0 };
 
int main() {
    int m, n;
    scanf("%d %d", &m, &n);
 
    for (int i = 1; i <= m; i++) {
        dp[i][0] = 1;
        dp[i][1] = i;
        dp[i][i] = 1;
    }
 
    for (int i = 2; i < m; i++) {
        for (int j = 2; j <= i; j++) {
            dp[i + 1][j] = dp[i][j - 1] + dp[i][j];
        }
    }
 
    ll rst = 0;
    for (int i = 0; i <= n; i++) {
        rst += dp[m][i];
    }
    printf("%lld", rst);
}