#include <iostream>
#include <iomanip>
using namespace std;
int p[6] = {2,3,5,7,11,13};
int g[6] = {4,6,8,9,10,12};
int main(){
    int n;cin>>n;
    int ans = 0;
    for(int i = 0; 6 > i; i++){
        for(int j = 0; 6 > j; j++){
            if(p[i]*g[j] == n)ans++;
        }
    }
    cout << fixed << setprecision(20) << (double)ans/36.0 << endl;
}