#include <cstdio>

int pow(int a, int n){
    if(n == 0) return 1;
    return pow(a, n-1) * a;
}

int main(){
    int K;
    int a[6] = {2,3,5,7,11,13};
    int b[6] = {4,6,8,9,10,12};
    int c = 0;
    
    scanf("%d", &K);
    
    for(int i = 0; i < 6; i++){
        for(int j = 0; j < 6; j++){
            if(a[i] * b[j] == K) c+=2;
        }
    }
    if(c != 0) printf("%f\n", (double)1 / pow(6, c));
    else printf("%f\n", 0.0);
    
    return 0;
}