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

public class Solution {

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

        
        System.out.println(n*m-1);
        /*long min = Math.min(n, m);

        if(min < 4) {
            System.out.println(n*m-1);
        } else {
            long pow = 4;
            long count = 0;
            while(min/pow > 0) {
                if(pow != 4) {
                    count = count * 4 + 2;
                }
                if(min != pow) {
                    pow *= 2;
                } else {
                    break;
                }
            }
            System.out.println((pow/4)*(pow/4)*14 + count + n*m-pow*pow);
        }*/
    }
}