#include <bits/stdc++.h>
using namespace std;
int main() {
  unsigned long long int H1, W1, H2[2], W2[2], ans1, ans2;
  int keta;
  cin >> H1 >> W1;
  H2[0] = H1 / 100000;
  W2[0] = W1 / 100000;
  H2[1] = H1 - (H1 / 100000) * 100000;
  W2[1] = W1 - (W1 / 100000) * 100000;
  ans1 = H2[0] * W2[0] + H2[1] * W2[0] / 100000 + H2[0] * W2[1] / 100000 +
         H2[1] * W2[1] / 10000000000;
  ans2 = (H2[1] * W2[1] - (H2[1] * W2[1] / 10000000000) * 10000000000) +
         (H2[1] * W2[0] - (H2[1] * W2[0] / 100000) * 100000) * 100000 +
         (H2[0] * W2[1] - (H2[0] * W2[1] / 100000) * 100000) * 100000;
  if (ans1 == 0)
    cout << ans2 / 2 + ans2 % 2 << endl;
  else {
    cout << ans1 / 2;
    if (ans1 % 2 == 1) ans2 += 5000000000;
    if (ans2 != 0) keta = floor(log10(ans2) + 1);
    if (ans2 == 0) keta = 0;
    for (int i = 0; i < 11 - keta; i++) {
      cout << 0;
    }
    cout << ans2 / 2 + ans2 % 2 << endl;
  }
  return 0;
}
