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 a = BigInteger.valueOf(n);
        BigInteger b = BigInteger.valueOf(m);

        BigInteger output = a.multiply(b).subtract(BigInteger.ONE);
        System.out.println(output.longValue());

    }
}