#include <bits/stdc++.h>
using namespace std;

int prime[] = { 2, 3, 5, 7, 11, 13 };
int comp[] = { 4, 6, 8, 9, 10, 12 };

signed main(){
  int K; cin >> K;
  int cnt = 0;
  for( int i = 0; i < 6; ++i )
    for( int j = 0; j < 6; ++j )
      cnt += prime[ i ] * comp[ j ] == K;
  cout << fixed << setprecision( 13 ) << 1.0 * cnt / 36 << endl;
  return 0;
}