Problem:
Toggling Cases

Write a program which converts uppercase/lowercase letters to lowercase/uppercase for a given string.

Input

A string is given in a line.

Output

Print the converted string in a line. Note that you do not need to convert any characters other than alphabetical letters.

Constraints

The length of the input string < 1200

Sample Input

fAIR, LATER, OCCASIONALLY CLOUDY.

Sample Output

Fair, later, occasionally cloudy.

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace _8_A
{
    class Program
    {
        static void Main(string[] args)
        {
            string a = Console.ReadLine();
            for(int i = 0; i < a.Length; i++)
            {
                string y = a.Substring(i,1);
                if (char.IsLetter(a, i))
                {
                    if (char.IsUpper(a, i))
                    {
                        Console.Write(y.ToLower());
                    }
                    else
                    {
                        Console.Write(y.ToUpper());
                    }
                }
                else { Console.Write(y); }
            }Console.WriteLine();
        }
    }
}