#include <iostream>

int main()
{
    int d;
    std::cin >> d;
    
    if(d < 4)
    {
        std::cout << "0" << std::endl;
        return 0;
    }
    
    int s1, s2;
    s1 = s2 = d / 4;
    d %= 4;
    s2 += d / 2;
    
    std::cout << (int)(s1 * s2) << std::endl;
    
    return 0;
}