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 length = BigInteger.valueOf(n);
        BigInteger bigInt = length.multiply(BigInteger.valueOf(m));
        System.out.println(bigInt.subtract(BigInteger.ONE));
    }
}