#include <bits/stdc++.h>
using namespace std;
void io() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
}
template <typename K>
unordered_set<K> hashset() {
  unordered_set<K> s;
  s.max_load_factor(0.25);
  s.reserve(512);
  return s;
}
template <typename K, typename V>
unordered_map<K, V> hashmap() {
  unordered_map<K, V> m;
  m.max_load_factor(0.25);
  m.reserve(512);
  return m;
}
const long long inf = 10000000000000ll;
int ceil_div(long long x, long long y) { return 1 + ((x - 1) / y); }
int main() {
  io();
  long long h, w;
  cin >> h >> w;
  if (h == 1 || w == 1) {
    cout << 1 << endl;
  } else {
    cout << ceil_div(h, 2) * ceil_div(w, 2) +
                (ceil_div(h, 2) - 1) * (ceil_div(w, 2) - 1)
         << endl;
  }
}
