Goal
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.
https://en.wikipedia.org/wiki/Parsing
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
Input will consist of a single line, representing a possible expression in T++.
Output
You should output the length of the longest prefix that is valid or 0 if there is not such a prefix
Constraints
1 ≤ The length of line ≤ 100
