//{{{
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(...) repN((__VA_ARGS__,rep3,rep2,loop,~))(__VA_ARGS__)
#define loop(n) rep2(_loop_,n)
#define rep2(i,n) rep3(i,0,n)
#define rep3(i,begin,end) for(int i=(int)(begin),i##_end=(int)(end);i<i##_end;++i)
#define repN(a) repX a
#define repX(a0,a1,a2,x,...) x
const int MOD = 1e9+7;
//}}}

int l[6];
int main(void){
	int K;
	cin >> K;
	const int p[] = {2,3,5,7,11,13};
	const int c[] = {4,6,8,9,10,12};
	int ans = 0;
	rep(i, 6){
		rep(j, 6){
			if(p[i] * c[j] == K) ans++;
		}
	}
	printf("%.15f\n", ans / 36.0);
	return 0;
}