Problem:
Counting Characters

Write a program which counts and reports the number of each alphabetical letter. Ignore the case of characters.

Input

A sentence in English is given in several lines.

Output

Prints the number of alphabetical letters in the following format:

a : The number of 'a'
b : The number of 'b'
c : The number of 'c'
.
.
z : The number of 'z'

Constraints

The number of characters in the sentence < 1200

Sample Input

This is a pen.

Sample Output

a : 1
b : 0
c : 0
d : 0
e : 1
f : 0
g : 0
h : 1
i : 2
j : 0
k : 0
l : 0
m : 0
n : 1
o : 0
p : 1
q : 0
r : 0
s : 2
t : 1
u : 0
v : 0
w : 0
x : 0
y : 0
z : 0

Solution in C# (judge verdict: Runtime Error)

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

namespace ITP1_8_C
{
    class Program
    {

        static void Main(string[] args)
        {
            var alphabet = "abcdefghijklmnopqrstuvwxyz";
            var sumOfAlphabets = new int[alphabet.Length];

            var isContinued = true;
            while (isContinued)
            {
                var input = Console.ReadLine();
                if (input.Length == 0)
                {
                    return;
                }

                input = input.ToLower();

                foreach (var n in input) 
                {
                    if (n == '.')
                    {
                        isContinued = false;
                        break;
                    }

                    var index = alphabet.IndexOf(n);
                    if (0 <= index)
                    {
                        ++sumOfAlphabets[index];
                    }
                }
            }

            for (var i = 0; i < alphabet.Length; ++i)
            {
                Console.WriteLine("{0} : {1}", alphabet[i], sumOfAlphabets[i]);
            }
        }
    }
}