using System;
using System.IO;

class GFG{

public static void Main(string[] args)
{
    Random res = new Random();

    String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    String FileText = "";
    String randomstring = "";
    for (int i = 0; i < 1000; i++){
        for (int a = 0; a < 7; a++)
        {

          int x = res.Next(str.Length);
          randomstring = randomstring + str[x];
        }
        FileText = FileText + $"{randomstring}\n";
        Console.WriteLine("Random alphanumeric String:" + randomstring);
    }

    string file = @"codes.txt";
    File.WriteAllText(file, FileText );

}
}

using System;
using System.IO;

class GFG{

public static void Main(string[] args)
{
    Random res = new Random();

    String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    String FileText = "";
    String randomstring = "";
    for (int i = 0; i < 1000; i++){
        for (int a = 0; a < 7; a++)
        {

          int x = res.Next(str.Length);
          randomstring = randomstring + str[x];
        }
        FileText = FileText + $"{randomstring}\n";
        Console.WriteLine("Random alphanumeric String:" + randomstring);
    }

    string file = @"codes.txt";
    File.WriteAllText(file, FileText );

}
}