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 in = new Scanner(System.in);
        long n = in.nextInt();
        long m = in.nextInt();
        long count = 0;
        long temp = Math.min(n,m);
        long temp2;
        
        count = temp - 1;
        temp2 = Math.max(n,m);
        count += (temp2 - 1) * temp;
        System.out.println(count);
    }
}