#include <stdio.h>

int main(void){
    int i, j, K, cnt = 0;
    int a[] = {2, 3, 5, 7, 11, 13}, b[] = {4, 6, 8, 9, 10, 12};
    double ans;
    scanf("%d", &K);
    for(i=0;i<6;i++){
        for(j=0;j<6;j++){
            if(a[i]*b[j]==K){
                cnt++;
            }
        }
    }
    ans = cnt / 36.0;
    printf("%.13lf\n", ans);

    return 0;
}