#include<stdio.h>
main(){
    int prime[] = {2,3,5,7,11,13};
    int comp[] = {4,6,8,9,10,12};
    int N;
    scanf("%d",&N);
    int count=0;
    for(int i = 0;i < 6;i++){
        for(int j = 0;j < 6;j++){
            if(N == prime[i]*comp[j])count++;
        }
    }
    printf("%.12lf\n",1.*count/36);
    
}