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) 
    {
          Scanner sc = new Scanner(System.in);
          long n = sc.nextLong();
          long m = sc.nextLong();
          long cnt=0;
          //long row = (n-1);
          //long col = (m -1)*m;
          long tot = (n*m)-1;
          System.out.println(tot);
    }
}