#include <bits/stdc++.h>

using namespace std;
typedef unsigned long long ull;
ull fact(int n){
    if(n==0 || n==1)
        return 1;
    return (n*fact(n-1));
}
ull c(int k,int x){
    return (fact(k)/(fact(k-x)*fact(x)));
}
long countArray(int n, int k, int x) {
    ull ans=c(k,n-2);
    ans=(ans*fact(n-2));
    ull ans1=c(k-1,n-3);
    ans1=(ans1*fact(n-3));
    ull ans2=c(k-1,n-4);
    ans2=ans2*fact(n-4);
    ans=ans-(ans1+ans2);
    
    return ans;
    // Return the number of ways to fill in the array.
}

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