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Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.



Ted wants to develop a compiler and knows that one of the most important elements in a compiler is its parser

Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar.

Today, Ted is concerned with an abstract instruction which is composed of the characters < and > , which he will use on the design of his language, T++ :D.

He understand that, for an expression to be valid, a < symbol must always have a matching > character somewhere (nested expression are valid) after it. In addition, each > symbol must exactly match a < symbol.

So, for instance, the instructions:




are all valid. While:



are not.

Given expression which represent some instructions to be analyzed by Ted's compiler, you should tell the length of the longest prefix of this expression that is valid, or 0 if there is not such a prefix.
Input will consist of a single line, representing a possible expression in T++.
You should output the length of the longest prefix that is valid or 0 if there is not such a prefix
1 ≤ The length of line ≤ 100

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