using System;
using System.Collections.Generic;
using System.IO;
class Solution
{
    static void Main(String[] args)
    {
        int[] tempArr = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
        long n = tempArr[0];
        long m = tempArr[1];
        long cut = n*m-1;
        Console.WriteLine(cut);
    }
}