using System;

public class Program

{

    public static void Main()

    {

        string str = "fGm&pHel2T";

        string expected = "fgm&phel2t";

        string result = ToLowerCase(str);

        Console.WriteLine("Expected: {0}", expected);

        Console.WriteLine("Result: {0}", result);

    }

    public static string ToLowerCase(string str) {

        char[] chars = str.ToCharArray();

        for (int i = 0; i < chars.Length; i++)

        {

            if ('A' <= chars[i] && chars[i] <= 'Z') {

                int n = (int)chars[i];

                chars[i] = (char)(n + 32);

            }

        }

        return new string(chars);

    }

}