import std;

int calc(int d) {
    // 縦 x, 横 y とすると x + y <= d/2
    int s = d / 2;
    int x = s / 2;
    int y = s - x;
    return x * y;
}

void main() {
    int d; scan(d);
    writeln(calc(d));
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;