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|2 초||512 MB||76||56||51||71.831%|
A string of lowercase letters is called alphabetical if some of the letters can be deleted so that the only letters that remain are the letters from `a' to `z' in order.
Given a string s, determine the minimum number of letters to add anywhere in the string to make it alphabetical.
Each input will consist of a single test case. Note that your program may be run multiple times on different inputs. The only line of input contains a string s (1 ≤ |s| ≤ 50) which contains only lowercase letters.
Output a single integer, which is the smallest number of letters needed to add to s to make it alphabetical.