using System.Text;

int min = int.MaxValue;

int[] numbers = File.ReadAllLines("/var/data/data.txt").Select(x=> int.Parse(x)).ToArray();

foreach(var number in numbers)
{
    if (number < min)
    {
        min = number;
    }
}

string result = Convert.ToString(Math.Pow(min, 3));

using (FileStream fstream1 = new FileStream("/var/result/result.txt", FileMode.OpenOrCreate))
{
    fstream1.SetLength(0);
    byte[] buffer1 = Encoding.Default.GetBytes(result);
    await fstream1.WriteAsync(buffer1, 0, buffer1.Length);
}

Console.WriteLine(result);