#include <stdio.h>
int main(void){
    double d=0;
    int c[]={4,6,8,9,10,12},p[]={2,3,5,7,11,13},i,j,a;
    scanf("%d",&a);
    for(i=0;i<6;i++)for(j=0;j<6;j++)if(a==c[i]*p[j])d++;
    printf("%.20lf\n",d/36);
    return 0;
}