#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
long long a1,a2;
int main() 
{
   cin>>a1>>a2;
 
    if (a1>a2) swap(a1,a2);
    
    if (a1==1 && a2==1) cout<<0<<endl;
        else
    if (a1==1) cout<<a2-1<<endl;
        else cout<<(a2-1)+(a1-1)*a2<<endl;
          
            
    
    
    return 0;
}