#include <stdio.h>
#include <iostream>
#include <stdlib.h>
#include <string>
#include <string.h>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <assert.h>
#include <algorithm>
#include <iomanip>
#include <time.h>
#include <math.h>
#include <bitset>

#pragma comment(linker, "/STACK:256000000")

using namespace std;

typedef long long int int64;
typedef long double double80;

const int INF = (1 << 29) + 5;
const int64 LLINF = (1ll << 59) + 5;
const int MOD = 1000 * 1000 * 1000 + 7;

int64 n, m;

map<pair<int, int>, int64> ans;

int64 get_ans(int64 x, int64 y)
{
	if (x > y)
		swap(x, y);
	if (x == 0)
		return 0;
	if (x == 1)
		return y - 1;

	if (ans.count(make_pair(x, y)))
		return ans[make_pair(x, y)];

	if (y & 1)
		return 1 + y + 2 * get_ans(x, y / 2);
	else
		return 1 + 2 * get_ans(x, y / 2);
}

int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);

	cin >> n >> m;

	cout << n * m - 1;

	fclose(stdin);
	fclose(stdout);

	return 0;
}