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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    long long n,m;
    cin>>n>>m;
    if(n==1 && m==1)
        cout<<"0"<<endl;
    else{
        if(n==1)
        {cout<<m-1<<endl;}
        else{
    if(m==1)
        cout<<n-1<<endl;
    else{
        
       cout<<(long long) (min(n,m)-1)+min(n,m)*(max(n,m)-1);
    }
    }
    }
    return 0;
}