#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
//libs
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <string>
#include <map>
#include <complex>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <queue>

using namespace std;
//defines
#define infll 8e18
#define ll long long
#define itn ll
#define vi vector<itn>
#define vvi vector<vi>
#define pii pair<itn,itn> 
//constants
const double eps = 1e-7;
const ll mod = 1000000007;
//end of definition


void solve()
{
	ll n, m;
	cin >> n >> m;
	if (n == 1 && m == 1)
	{
		cout << 0;
		return;
	}
	if (n == 1 || m == 1)
	{
		cout << max(n, m) - 1 << endl;
		return;
	}
	
	cout << max(n, m)-1+(min(n,m)-1)*max(n,m) << endl;



}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
#ifdef _DEBUG
	freopen("input.txt", "r", stdin);
	//freopen("input.txt", "w", stdout);
#endif
	solve();

	return 0;
}