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