#include <iostream>
#include <iomanip>
using namespace std;
int main(void){
    int numerator = 0;
    int prime[6] = {2, 3, 5, 7, 11, 13};
    int synth[6] = {4, 6, 8, 9, 10, 12};
    int dice; cin >> dice;
    
    for(int i=0; i<6; i++){
        for(int j=0; j<6; j++){
            if(dice == (prime[i] * synth[j])){
                numerator++;
            }
        }
    }
    cout << fixed << setprecision(17) << (numerator / 36.0) << endl;
}