#include <bits/stdc++.h>

#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define endl "\n"
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = ((int)(n)-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()

using namespace std;
using ll = long long;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> P;
 
const int INF = 1e9;
//const ll INF = 1e18;
const double EPS = 1e-10;
const int MOD = 1e9+7;
const double PI = acos(-1.0);

int main()
{
	int x[] = {2,3,5,7,11,13},y[] = {4,6,8,9,10,12};
	int k; cin >> k;
	int cnt[200]; fill(cnt,cnt+200,0);
	for(int i = 0; i < 6; i++){
		for(int j = 0; j < 6; j++){
			cnt[x[i]*y[j]]++;
		}
	}
	cout << fixed << setprecision(12) << cnt[k]/36.0 << endl;
	return 0;
}