Letter Frequency Counter

Given a string s consisting solely of lowercase letters, compute the frequency of each letter in s.

The output should contain one line per distinct letter found in s, formatted as letter: frequency. The letters must appear in alphabetical order. Mathematically, the frequency of a letter \( c \) can be defined as:

$$ f(c) = \text{number of occurrences of } c \text{ in } s $$

For example, for s = "banana", the output should be:

a: 3
b: 1
n: 2

inputFormat

The input consists of a single line containing a non-empty string s (1 ≤ |s| ≤ 10⁵) that includes only lowercase English letters.

outputFormat

For each distinct letter in s (sorted in alphabetical order), output a line in the format letter: frequency without extra spaces.

## sample

banana

a: 3
b: 1
n: 2

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