import java.util.*;
import java.math.*;
public class Hack42_1 {
	
 static Scanner sc = new Scanner(System.in);
 static int mod = 1000000007;	
 
 public static void main(String[] args)
 {
	 long n = nl();
	 long m = nl();
	 System.out.println((n*m)-1);
 }
 
 static long[] la(int x)
 {
	 long[] a = new long[x];
	 for(int i=0;i<x;i++)
		 a[i]=sc.nextLong();
	 return a;
 }
 
 static int[] ia(int x)
 {
	 int[] a = new int[x];
	 for(int i=0;i<x;i++)
		 a[i]=sc.nextInt();
	 return a;
 }
 
 static char[] ca()
 { return sc.next().toCharArray(); }
 
 static int ni()
 { return sc.nextInt();}
 
 static long nl()
 { return sc.nextLong();}
 
 static double nd()
 { return sc.nextDouble();}
 
}