#include using namespace std; #define REP(i,a,b) for(int i=a;i<(int)b;i++) #define rep(i,n) REP(i,0,n) int main() { int n; cin >> n; int mx = -1<<29; REP(K, 1, n/2) { int N = n; N -= 2*K; N /= 2; mx = max(mx, K*N); } cout << mx << endl; return 0; }