#include <bits/stdc++.h>

using namespace std;

//long countArray(int n, int k, int x) {
    // Return the number of ways to fill in the array.
//}
long long int factorial(int k)
{
    int fact=1;
    while(k>1)
    {
        fact=fact*k;
        k--;
    }
    return fact;
}

int main() {
    int n;
    int k;
    int x;
    cin >> n >> k >> x;
    if(k>(n-2))
    {
        long long int a=factorial(k);
        long long int b=factorial((n-2));
        long long int c=factorial((k-n+2));
        cout<<(a/(b*c))<<endl;
    }
    
    //long answer = countArray(n, k, x);
    //cout << answer << endl;
    return 0;
}