#include<iostream>
#include<stdio.h>
#include<vector>

using namespace std;

int main(){
    vector<int> sosu{2, 3, 5, 7, 11, 13};
    vector<int> gose{4, 6, 8, 9, 10, 12};

    vector<int> seki(36);

    for(int i=0; i<6; i++){
        for(int j=0; j<6; j++){
            seki[6*i+j] = sosu[i]*gose[j];
        }
    }

    int k;
    cin>> k;

    int cnt = 0;
    for(int i=0; i<36; i++){
        if(k==seki[i]){
            cnt++;
        }
    }
    
    printf("%.14f\n", cnt/36.0);

    return 0;
}