#include <iostream>
#include <vector>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n); i++)


int bs(int k, int pre, int com){
    if(k == pre * com) return true;
    return false;
}

int main(){
    int cnt = 0;
    int k = 0; cin >> k;
    int pre[6] = {2,3,5,7,11,13};
    int com[6] = {4,6,8,9,10,12};
    rep(i,6){
        rep(j,6){
            if(bs(k,pre[i],com[j])) cnt++;
        }
    }
    double res = double(cnt) / double(36);
    printf("%.20f\n",res);

    return 0;
}