#include <bits/stdc++.h>

using namespace std;

int fact(int x){
    long f=1;
    for(int i = 2; i <=x; ++i)
    {
        f *= i;
    }
    return f;
}

long countArray(int n, int k, int x) {
    // Return the number of ways to fill in the array.
    return (fact(n-2)/fact(n-k-2))+1;
}

int main() {
    int n;
    int k;
    int x;
    cin >> n >> k >> x;
    long answer = countArray(n, k, x);
    cout << answer << endl;
    return 0;
}