using System;
public class exercise13
{
    public static void Main()
    {
        string str1;
        char[] arr1;
        int l,i;
        l=0;
        char ch;
        Console.Write("\n\nReplace lowercase characters by uppercase and vice-versa :\n");
        Console.Write("--------------------------------------------------------------\n");
        Console.Write("Input the string : ");
        str1 = Console.ReadLine();
        l=str1.Length;
        arr1 = str1.ToCharArray(0, l); // Converts string into char array.
        Console.Write("\nAfter conversion, the string is : ");
        for(i=0; i < l; i++)
            {
                ch=arr1[i];
                if (Char.IsLower(ch)) // check whether the character is lowercase
                    Console.Write(Char.ToUpper(ch)); // Converts lowercase character to uppercase.
                else
                    Console.Write(Char.ToLower(ch)); // Converts uppercase character to lowercase.
            }
        Console.Write("\n\n");
    }
}