#include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
const int MOD=100000;
int B=1000000;
int main(){
      int a[6]={2,3,5,7,11,13};
      int b[6]={4,6,8,9,10,12};
      int k,cnt=0;
      cin>>k;
      REP(i,6)REP(j,6)if(a[i]*b[j]==k)cnt++;
      printf("%.10f\n",(double)cnt/36.0);
}