//By Don4ick
#include <bits/stdc++.h>

const long long INF = (long long)1e18+ 228;
using namespace std;
long long n, m, ans = INF;

int main()
{
	cin >> n >> m;
	
	if (n == 1 && m == 1)
		ans = 0;
	if (n == 1)
		ans = m - 1;
	if (m == 1)
		ans = n - 1;
	if (n != 1 && m != 1)
		ans = min((n - 1) + (n * (m - 1)), (m - 1) + (m * (n - 1)));
		
	cout << ans;

	return 0;
}