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 p = in.nextInt();
        if(p == 1){
        System.out.println(n - p);    
        }else{
        System.out.println(n*p - 1);    
        }
        
    }
}