using System;
using System.IO;
using System.Diagnostics;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1 {
    class Program {
        static void Main (string[] args) {
            int result = Directory.GetFiles( args[0] ).AsParallel().Select( (filename) => {
                return File.ReadLines(filename).Select(int.Parse).Sum();
            } ).Sum();
            
            Console.WriteLine( result );
        }
    }
}