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: Accepted)

using System;
using System.Linq;

namespace C_sharp
{
    class Program
    {
        static void Main(string[] args)
        {
            var alp_num = new int[26];
            
            while (true)
            {
                string line = Console.ReadLine();
                if (line == null)
                {
                    break;
                }

                foreach (char c in line.ToCharArray())
                {
                    if (Char.IsLetter(c))
                    {
                        alp_num[Char.ToLower(c)-97]++;
                    }
                }
            }

            var i = 97;
            foreach (var n in alp_num)
            {
                Console.WriteLine($"{(Char)i++} : {n}");
            }
        }
    }
}