while line = gets.chomp do
  strs = line.downcase.split("")
  arr = Array.new(26){0}
  strs.each{|s|
    i = s.ord - 97
    next if i < 0 || i > 25
    arr[i] += 1
  }
  ("a".."z").each{|s|
    printf "%s : %d\n", s, arr[s.ord-97]
  }
end