#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;

int main(void){
	int a[] = {2,3,5,7,11,13},b[] = {4,6,8,9,10,12};

    int k;
    cin >> k;
    int cnt =0;
    for(int i=0;i<6;i++){
        for(int j=0;j<6;j++){
            if(a[i]*b[j] == k)cnt++;
        }
    }
    cout <<fixed << setprecision(20) << cnt/36. << endl;

	return 0;
}