#include<iostream>

#define REP(i,n) for(i=0; i<n; i++)
#define ARRAY_LENGTH(array) (sizeof(array) / sizeof(array[0]))

using namespace std;

int main()
{
    int p_num[]={2,3,5,7,11,13};
    int c_num[]={4,6,8,9,10,12};
    int n=ARRAY_LENGTH(p_num);
    int i,j,k;
    double cnt=0.0;
    cin >> k;
    REP(i,n) {
        REP(j,n) {
            if(p_num[i]*c_num[j]==k) { cnt+=1.0; }
            else{}
        }
    }
    printf("%.12f\n",cnt/36.0);
    
    return 0;
}