#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <map>
#include <set>
#include <iomanip>
#include <vector>

using namespace std;

int main(int argc, char *argv[])
{
    long long int x_val, y_val, curr_max;
    cin >> x_val >> y_val;
    if(x_val == 1 && y_val == 1)
        cout << 0 << endl;
    else if(x_val == 1)
        cout << y_val -1 << endl;
    else if(y_val == 1)
        cout << x_val - 1 << endl;
    else
        cout << max(x_val, y_val)-1 + max(x_val,y_val)*(min(x_val,y_val)-1) << endl;

    return 0;
}