Field of Wonders

Petryk and Marichka enjoy playing the game "Field of Wonders." In this game, Marichka writes down a word using uppercase English letters, and Petryk attempts to guess it. Each time Petryk guesses a letter correctly, it is revealed in all positions where it appears in the word. What is the minimum number of guesses Petryk needs to identify the entire word?

Input: A word composed of uppercase English letters, with a maximum length of 100 characters.

Output: The minimum number of guesses required to reveal the entire word.

Examples