#include <stdio.h>
#include <iso646.h>

int main(void) {
    double dice = 0;
    int composite[] = {4, 6, 8, 9, 10, 12}, prime[] = {2, 3, 5, 7, 11, 13};
    int i, j, ans;
    scanf("%d", &ans);

    for (i = 0; i < 6; i++) {
        for (j = 0; j < 6; j++) {
            if (ans == composite[i] * prime[j]) dice++;
        }
    }
    printf("%12.20lf\n", dice / 36);
    return 0;
}