#include <iostream>
#define ll long long
using namespace std;
ll K, N;
ll ar[110][110];
ll f(ll n, ll k)
{
if (ar[n][k])
return ar[n][k];
if (k > n || k < 0 || n < 0)
return ar[n][k] = 0;
if (n == k)
return ar[n][k] = 1;
if (k == 1)
return ar[n][k] = n;
return ar[n][k] = f(n - 1, k - 1) + f(n - 1, k);
}
int main()
{
cin >> K >> N;
if (N == 1)
cout << 1;
else
cout << f(N - 1, K - 1);
}