#include <bits/stdc++.h>
using namespace std;

int main()
{
	int K;
	cin >> K;

	int p[6] = { 2, 3, 5, 7, 11, 13 };
	int np[6] = { 4, 6, 8, 9, 10, 12 };
	double ans = 0;
	for( int i = 0; i < 6; i++ ) {
		for( int j = 0; j < 6; j++ ) {
			if( p[i] * np[j] == K ) ans++;
		}
	}
	ans /= 6 * 6;

	cout << fixed << setprecision(18) << ans << endl;
}