import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

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 in=new Scanner(System.in);
        long m=in.nextLong();
        long n=in.nextLong();
        if(n==1 && m==1)
            System.out.println(0);
        else if(m==1)
            System.out.println(n-1);
        else if(n==1)
            System.out.println(m-1);
        else
           { 
            if(((m-1)+(m)*(n-1))<((m-1)*(n)+(n-1)))
            System.out.println((m-1)+(m)*(n-1));
        else
            System.out.println((m-1)*(n)+(n-1));
        }
    }
}