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 Python3 (judge verdict: Accepted)

import string
from collections import Counter

alphabet_list = string.ascii_lowercase

sentences = []
while True:
    try:
        sentence = input().lower()
        sentences.append(sentence)
    except EOFError:
        break

sentence_flatten = ''.join(sentences)

count_list = Counter(sentence_flatten)

for alphabet in alphabet_list:
    print(f'{alphabet} : {count_list[alphabet]}')