#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;
int INF = INT_MAX / 3;

int main() {
	vector<vector<double> > C(101, vector<double>(101));
	for (int i = 0; i <= 100; i++) {
		C[i][0] = 1;
		for (int j = 1; j <= i; j++)
			C[i][j] = C[i - 1][j] + C[i - 1][j - 1];
	}
	int N; cin >> N;
	if (N < 5) cout << 0 << endl;
	else printf("%.10f\n", C[94][N - 5] / C[99][N] * 12);
}