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 sc = new Scanner(System.in);
        int m = sc.nextInt();
        int n = sc.nextInt();
        BigInteger result;
        if (n == 1) {
            result = BigInteger.valueOf(m-1);     
        } else {
            result = BigInteger.valueOf(m-1).add(BigInteger.valueOf(n-1).multiply(BigInteger.valueOf(m)));
        }
         
        System.out.println(result.toString());
    }
}