Write a program which counts and reports the number of each alphabetical letter. Ignore the case of characters.
import sys
s = sys.stdin.read()
for c in ([chr(i) for i in range(97,97+26)] +[chr(i) for i in range(65,65+26)]):
    print('%s : %d' %(c, s.count(c)))
import sys
s = (sys.stdin.read()).lower()
for i in range(97,97+26):
    print('%s : %d' %(chr(i), s.count(chr(i))))