#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000000007
#define INF 1000000000 //(int)1e9
#define LLINF 2000000000000000000 //(ll)2e18
#define PI  3.1415926536

#define SIZE 1000

int main(){
    int num1[] = {2,3,5,7,11,13};
    int num2[] = {4,6,8,9,10,12};
    int k;
    int c[201]={0};
    
    for(int i=0;i<6;i++)
        for(int j=0;j<6;j++)
            c[num1[i]*num2[j]]++;
    
    scanf("%d",&k);
    
    printf("%.15lf\n",(double)c[k]/(6*6));
    
    return 0;
}