import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
   Scanner scan=new Scanner(System.in);
        long n=scan.nextLong();
        long m=scan.nextLong();
        if(n==1)
            {System.out.println(m-1);}
        else{
            if(m==1)
                {System.out.println(n-1);}
            else
            
            {
                System.out.println(m*n-1);
                
                
                
            }
            
        }
            
    
    
    
    }
}