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 in = new Scanner(System.in);
        BigInteger n = BigInteger.valueOf(in.nextLong());
        BigInteger m = BigInteger.valueOf(in.nextLong());
        System.out.println(n.multiply(m).subtract(BigInteger.ONE));
    }
}