#include<cstdio>
using namespace std;
int main(){
    double n; scanf("%lf", &n);
    if(n<5) printf("%d\n", 0);
    else printf("%.7lf\n", 12*n*(n-1)*(n-2)*(n-3)*(n-4)/99/98/97/96/95);
    return 0;
}