#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;


int main(void) {
	int k;
	int a, b;
	double sum=0;

	cin >> k;
	FOR(i, 1, 6) {
		FOR(t, 1, 6) {
			switch (i) {
			case 1:
				a = 2;
				break;
			case 2:
				a = 3;
				break;
			case 3:
				a = 5;
				break;
			case 4:
				a = 7;
				break;
			case 5:
				a = 11;
				break;
			case 6:
				a = 13;
				break;
			}
			switch (t) {
			case 1:
				b = 4;
				break;
			case 2:
				b = 6;
				break;
			case 3:
				b = 8;
				break;
			case 4:
				b = 9;
				break;
			case 5:
				b = 10;
				break;
			case 6:
				b = 12;
				break;
			}
			if (a*b == k) {
				sum++;
			}
		}
	}
	printf("%.15lf\n", sum / 36);
	return 0;
}