#include<iostream>
using namespace std;
int solve(int n, int m) {
int i, sum;
if (m == 1) return 1;
sum = 0;
for (i = 1; i < n; i++)
sum += solve(i, m - 1);
return sum;
}
int main( ) {
int n, m;
cin >> n >> m;
cout << solve(n, m) << endl;
return 0;
}
输入：7 4
输出：1
