#include <iostream>

using namespace std;

int main()
{
    long long n, k, x;
    cin >> n >> k >> x;
    
    long long pro = 1;
    
    if (k > n-2)
    {
        for (long long i = n-1; i <= k; i++)
        {
            pro = pro * i;
        }
    }
    else if (k < n-2)
    {
        for (long long i = k-1; i <= n-2; i++)
        {
            pro = pro * i;
        }
    }
    else if (k == n-2)
        pro = 1;
    
    cout << pro;
}