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) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
               Scanner in = new Scanner(System.in);

        BigDecimal n = in.nextBigDecimal();
    	
        BigDecimal m = in.nextBigDecimal();
    	
    	//System.out.println("n =="+n); // 3
    	
    	//System.out.println("m =="+m); //2
    	
    	BigDecimal columnCut = m.subtract(new BigDecimal(1));
    	BigDecimal rowCut = (n.subtract(new BigDecimal(1))).multiply(m);
    	
    	//BigDecimal totalCut = 
    	
    	System.out.println(columnCut.add(rowCut));
    }
}