#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

double logfact[100];

double perm(int a, int b) {
    double res = 1;
    rep (i, b) res *= a - i;
    return res;
}

int main() {
    int N;
    cin >> N;
    
    double ans = 12 * perm(N, 5) / perm(99, 5);
    printf("%.12f\n", ans);
    return 0;
}