#include <iostream>
using namespace std;
typedef long long ll;

ll P(int n, int k){
	ll res = 1;
	for(int i=0;i<k;i++)res *= n - i;
	return res;
}

int main(){
	int N;
	cin >> N;

	ll num = P(N, 5);
	ll den = P(99, 5);

	double res = 12.0 * num / den;
   	printf("%.10f\n", res);

	return 0;
}