#include <cstdio>
#include <initializer_list>
int main()
{
    int k;
    scanf("%d", &k);
    
    int res=0;
    for(int x: {2, 3, 5, 7, 11, 13})
        for(int y: {4, 6, 8, 9, 10, 12})
            res+=x*y==k;
    printf("%.13f\n", res/36.);
}