#include <bits/stdc++.h>
using namespace std;
int main() {
  int64_t H, W;
  cin >> H >> W;
  int64_t h, w;
  if (H % 2 == 1) {
    h = H / 2 + 1;
  } else {
    h = H / 2;
  }
  if (W % 2 == 1) {
    w = W / 2 + 1;
  } else {
    w = W / 2;
  }
  if (H == 1 or W == 1) {
    cout << 1;
    exit(0);
  }
  if (H % 2 == 1 and W % 2 == 0) {
    cout << h * w + (h - 1) * w;
  } else if (W % 2 == 1 and H % 2 == 0) {
    cout << h * w + (w - 1) * h;
  } else if (H % 2 == 1 and W % 2 == 1) {
    cout << h * w + (h - 1) * (w - 1);
  } else {
    cout << h * w + h * w;
  }
}
