#include <algorithm>
#include <vector>
#include <cfloat>
#include <string>
#include <cmath>
#include <set>
#include <cstdlib>
#include <map>
#include <ctime>
#include <iomanip>
#include <functional>
#include <deque>
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <stack>
#include <climits>
#include <sys/time.h>
#include <cctype>

using namespace std;

typedef long long ll;

int main() {
  int n;
  scanf("%d", &n);
  if (n < 5) {
    puts("0");
    return 0;
  }

  double a, b;
  a = b = 1;
  for (int i = 0; i < 5; i++) {
    a *= (99-i);
    b *= (n-i);
  }
  for (int i = 0; i < 5; i++) {
    a /= i+1;
    b /= i+1;
  }
  printf("%.12lf\n", (b*12.)/a);
  return 0;
}