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 sc=new Scanner(System.in);
        long n=sc.nextLong();
        long m=sc.nextLong();
        long count1=0,count2=0;
        count1=(m-1)*n;
        count2=count1+n-1;
        System.out.println(count2);
    }
}