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 scan = new Scanner(System.in);
        long i = scan.nextLong();
        long j = scan.nextLong();
        long count = 0;
        long count1 = 0;
        if(i==1){
            count = j - 1;
            System.out.println(count);
        }
        else if(j==1){
            count = i - 1;
            System.out.println(count);
        }
        else{
            if(i<j){
                count = i - 1;
               /* for(long k=0;k<count;k++){
                    for(long l=0;l<j;l++)
                        count = count + 1;
                }*/
                count1 = count1 + j;
                count1--;
                count = count + count1 * (count+1);
                
                System.out.println(count);
            }
            else{
                count = j - 1;
                count1 = count1 + i;
                count1--;
                count = count + count1 * (count+1);
                System.out.println(count);
            }
        }
        
            
    }
}