#include <stdio.h>

int main(){
    int N, i, j, cnt = 0;
    int sosu[6] = {2, 3, 5, 7, 11, 13};
    int gose[6] = {4, 6, 8, 9, 10, 12};
    double prob;

    scanf("%d", &N);
    for(i = 0; i < 6; i++){
        for(j = 0; j < 6; j++){
            if(sosu[i]*gose[j] == N){
                cnt++;
            }
        }
    }
    prob = cnt/36.0;
    printf("%.12lf\n", prob);

    return 0;
}