#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,p,n)for(ll i=(ll)p;i<(ll)n;i++)
#define all(x)(x).begin(),(x).end()
#define edt(x1,y1,x2,y2)sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))
int main(){
	ll K;
	cin>>K;
	vector<ll> dicea={2,3,5,7,11,13},diceb={4,6,8,9,10,12};
	ll cnt=0;
	rep(i,0,6){
		rep(j,0,6){
			if(dicea[i]*diceb[j]==K)cnt++;
		}
	}
	cout<<fixed<<setprecision(15)<<(double)cnt/36<<endl;
}