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 sys

c_dict = {
'a':0, 'b':0, 'c':0, 'd':0, 'e':0, 'f':0, 'g':0,
'h':0, 'i':0, 'j':0, 'k':0, 'l':0, 'm':0, 'n':0,
'o':0, 'p':0, 'q':0, 'r':0, 's':0, 't':0, 'u':0,
'v':0, 'w':0, 'x':0, 'y':0, 'z':0
}

while True:
    a = sys.stdin.readline()
    if not a:
        break
    else:
        str = a.lower() #すべての文字を小文字に変換
        for i in str: #strの中身を一文字ずつiに入れる
            if i in c_dict: #c_dictにiが含まれているかどうか，含まれる→True，含まれない→False
                c_dict[i] = c_dict[i] + 1 #print(c_dict[i]) >>> 値
            """ #もし，辞書に無い文字を追加したければ，これでできる（appendしなくていいの利点）
            else:
                c_dict[i] = 1
            """

for i in c_dict:
    print(i,':',c_dict[i])