#include <iostream>

using namespace std;

int main()
{
    long long n, m;
    cin >> n >> m;
    if (n == 1) {
        cout << m - 1  << endl;
    } else if (m == 1) {
        cout << n - 1 << endl;
    } else {
        cout << m * n - 1 << endl;
    }
    return 0;
}