#include<bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;
    array<double, 100> fact;
    fact[0] = 1;
    for(int i = 1; i < 100; i++)fact[i] = i * fact[i - 1];
    auto comb = [&](int n, int k){
        if(n < k)return 0.0;
        return fact[n] / (fact[n - k] * fact[k]);
    };
    printf("%.15lf\n", 12 * comb(n, 5) / comb(99, 5));
}