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 scan = new Scanner(System.in);
        int row, column;
        row = scan.nextInt();
        column = scan.nextInt();
        int numOfCut = 0, count = 0;
        int numCutRow = 0;
        numCutRow = row - 1;
        if (column != 1 && column != 0){
            numOfCut = column - 1;
        }
        if (row != 1){
            while (count < column){
                numOfCut = numOfCut + numCutRow;
                count++;
            }
        }
        System.out.println(numOfCut);
    }
}