using System;
using System.IO;

class Program
{
    static void Main()
    {
        string dataDirectory = "/var/data";
        string outputFile = "/var/result/data.txt";

        string[] fileLines = Directory.GetFiles(dataDirectory);

        using (StreamWriter writer = new StreamWriter(outputFile))
        {
            foreach (string filePath in fileLines)
            {
                string[] lines = File.ReadAllLines(filePath);

                if (lines.Length > 0)
                {
                    writer.WriteLine(lines[0]);
                }
            }
        }

        Console.WriteLine("Файл успешно сформирован!");
    }
}