#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <math.h>
 
int main(void){
    int yyes=0;
int k,a[10]={2,3,5,7,11,13},b[10]={4,6,8,9,10,12};
scanf("%d",&k);
for(int i=0;i<6;i++){
    for(int j=0;j<6;j++){
        if(a[i]*b[j]==k){yyes++;}
    }
}
if(yyes==0){printf("0\n");return 0;}
printf("%.25lf\n",yyes/36.0);
}