#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <set>
#include <map>
#include <iomanip>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;

int main() {

  static long double C[111][111];
  rep(i, 100) {
    C[i][0] = 1;
    REP(j, 1, i+1) {
      if(i-1 >= 0) C[i][j] += C[i-1][j];
      if(i-1 >= 0) C[i][j] += C[i-1][j-1];
    }
  }

  int N;
  cin >> N;

  if(N < 5) {
    cout << 0 << endl;
  }
  else {
    cout << setprecision(7) << ( 12.0 * C[N][5] / C[99][5] ) << endl;
  }

  return 0;
}