#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <unordered_map>
#include <map>
#include <queue>
#include <cstdlib>
using namespace std;

int main()
{
	int W, H; cin >> W >> H;

	int m = min(W, H);
	int M = max(W, H);
	
	int cost = 0;
	int x = 3;
	for (int i = 1; i <= m; i++) {
		cost += x;
		if (i % 2 == 0)x += 4;
	}


	for (int i = 0; i < M-m; i++)cost += m + m%2;

	cout << cost+(M>m && m%2==0) << endl;
	
	return 0;
}