import java.io.*;
import java.util.*;
import java.math.*;
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 n=sc.nextInt();
        int m=sc.nextInt();
        double x=((double)n*(double)m);
        String s=String.format("%.0f", x);
         BigInteger bg1 = new BigInteger(s);
        BigInteger bg2 = new BigInteger(""+1);
        bg1=bg1.subtract(bg2);
        //String s=String.format("%.0f", x);
        System.out.println(bg1+"");
    }
}