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

public class Solution {

    public static void main(String[] args) {
       Scanner sc=new Scanner(System.in);
        long n=sc.nextLong();
        long m=sc.nextLong();
        if (m!=n){

            System.out.println(m-1+((n-1)*(m)));
        }
         else {
            if (m>2){
            System.out.println((m-1)+(m-1)*m);
            }
            if (m==1){
                System.out.println("0");
            }
            if (m==2){
                System.out.println("2");
            }
        } 
    }
}