#include <stdio.h>
int main(){
    //input
    int K;
    scanf("%d",&K);

    //search
    int count = 0;
    int pDice[6] = {2,3,5,7,11,13};
    int sDice[6] = {4,6,8,9,10,12};
    for (int i = 0;i < 6;i++){
        for (int j = 0;j < 6;j++){
            if (pDice[i]*sDice[j] == K){
                count++;
            }
        }
    }

    //output
    printf("%f\n",count/36.0);
    return 0;
}