#include <bits/stdc++.h>
int main() {
  unsigned long long w, h;
  unsigned long long moves = 0;
  scanf("%llu %llu", &w, &h);
  if (w == 1 || h == 1) {
    printf("1");
  } else {
    moves += (w / 2) * (h / 2);
    moves += ((w / 2) + (w % 2)) * ((h / 2) + (h % 2));
    printf("%llu", moves);
  }
}
