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

map<tuple<int, int, bool>, int>dp;

int solve(int w, int h, int dir) {
	if (dp.find(make_tuple(w, h, dir)) != dp.end())return dp[make_tuple(w, h, dir)];

	int a, b;
	a = 2 * h + 1;
	b = 2 * w + 1;

	if (dir == 1)a--;
	else b--;

	if (h == 1 || w==0)return b;
	if (w == 1 || h==0)return a;

	int ans = max(a + solve(w - 2, h,1), b + solve(w, h - 2,0));

	dp[make_tuple(w, h, dir)] = ans;

	return ans;
}

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

	if (W == 0 && H == 0)cout << 0 << endl;
	else cout << max(solve(W,H,1), solve(W, H, 0)) << endl;

	return 0;
}