#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    
    long long int row, col;
    cin >> row >> col;
    
   long long int ans = 0;
        
        if (row ==1 && col ==1)
            ans = 0;
            
    else{
        ans = (row) * (col-1) + (row-1);
    }
            
    cout << ans << endl;
    return 0;
}