#include <iostream>
#include <cstdio>
using namespace std;

int main(){
	int n;
	int a[6] = {2,3,5,7,11,13};
	int b[6] = {4,6,8,9,10,12};
	double ans = 0;
	
	cin >> n;
	for( int i = 0; i < 6; i++ )
		for( int j = 0; j < 6; j++ )
			if( a[i] * b[j] == n )
				ans++;
	ans /= 36;
	printf("%.14f\n", ans);
	return 0;
}