#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	vector<int> prime = {2, 3, 5, 7, 11, 13};
	vector<int> composite = {4, 6, 8, 9, 10, 12};
	int K;
	cin >> K;
	
	int cnt = 0;
	REP(i, prime.size()) REP(j, composite.size()) cnt += prime[i] * composite[j] == K;
	printf("%.16f\n", (double)cnt/ (prime.size() * composite.size()));
}