#include <iostream>
#include <vector>
#include <map>
#include<string>
#include<queue>
#include<math.h>
#define all(x) begin(x),end(x)
#define ll long long
#define P pair<int,int>
#define lP pait<ll,ll>
using namespace std;
int main() {
    double k,cnt=0;
    cin>>k;
    int dx[]={2,3,5,7,11,13};
    int dy[]={4,6,8,9,10,12};
    vector<double> a(36);
    for(int i=0;i<6;i++){
        for(int j=0;j<6;j++){
            int x=dx[i];int y=dy[j];
            a[i+j]=x*y;
            if(a[i+j]==k) cnt++;
        }
    }
    printf("%.15lf\n",cnt/36);
    return 0;
}