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

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 obj=new Scanner(System.in);
	int n,m;
	
	n=obj.nextInt();
	m=obj.nextInt();
	
	long res=(long)n*m;
	System.out.println(res-1);
	
            
            
    }
}