#include "iostream"
#include "vector"
using namespace std;

int main(){
    vector<int> prime = {2,3,5,7,11,13};
    vector<int> composite = {4,6,8,9,10,12};
    vector<int> freq(12*13+1);
    for (auto x : prime) for (auto y : composite) freq[x*y]++;
    int k;
    cin >> k;
    printf("%.12f\n",freq[k] / 36.0);
    return 0;
}