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);
        int n = in.nextInt();
        int m = in.nextInt();
        BigInteger n1=BigInteger.valueOf(n);
        BigInteger m1=BigInteger.valueOf(m);
        BigInteger val=(n1.multiply(m1)).subtract(BigInteger.valueOf(1));
        System.out.print(val);
    }
}