#include<iostream>
#include<string>
#include<cstring>
#include<complex>
#include<vector>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<iomanip>
using namespace std;

#define REP(i, j) for (int i = 0; i < (int)j; ++i)
#define FOR(i, j, k) for (int i = (int)j; i < (int)k; ++i)
#define SORT(v) sort(v.begin(), v.end())
#define REVERSE(v) reverse(v.begin(), v.end())
typedef complex<double> P;
typedef vector<int> VI;
typedef long long LL;
typedef pair<int,int> PII;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int p[] = {2,3,5,7,11,13};
	int c[] = {4,6,8,9,10,12};

	int k;
	cin >> k;

	int cnt = 0;
	REP(i,6) {
		REP(j,6) {
			if (p[i]*c[j] == k) cnt++;
		}
	}
	double ans = cnt / pow(6,2);

	printf("%.12lf",ans);

	return 0;
}