using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        string[] tokens_n = Console.ReadLine().Split(' ');
        long n = Convert.ToInt64(tokens_n[0]);
        long m = Convert.ToInt64(tokens_n[1]);
        
        Console.WriteLine((n*m)-1);
    }
}