#include <bits/stdc++.h>
using namespace std;
int main() {
  double h, w;
  cin >> h >> w;
  double ans;
  if (h == 1 || w == 1)
    ans = 1;
  else
    ans = (w / 100000 * (h + 1) / 100000) / 2 * 10000000000;
  cout << ans << "\n";
}
