PROBLEM STATEMENT

In this problem, a left single arrow is defined as a "less than" character ('<') immediately 
followed by zero or more consecutive hyphen characters ('-').  A left double arrow is a "less 
than" character ('<') immediately followed by zero or more consecutive equals characters ('=').  A 
right single arrow is zero or more hyphen characters ('-') immediately followed by a "greater 
than" character ('>').  A right double arrow is zero or more equals characters ('=') immediately 
followed by a "greater than" character ('>').  For example, the following are arrows (quotes for 
clarity only): "==>", "<-", "<", "<===", "--->", ">".  The length of an arrow is the number of 
characters it contains.

You will be given a string s.  Return the length of the longest arrow in s, or -1 if it does not 
contain any arrows.


DEFINITION
Class:Arrows
Method:longestArrow
Parameters:string
Returns:int
Method signature:int longestArrow(string s)


NOTES
-Arrows may overlap. See examples for further clarifications.


CONSTRAINTS
-s will contain between 1 and 50 characters, inclusive.
-Each character in s will be one of '<', '>', '-' or '='.


EXAMPLES

0)
"<--->--==>"

Returns: 4

The arrows contained in s in this case are, by order of appearance:
"<", "<-", "<--", "<---", "--->", "-->", "->", ">", "==>", "=>" and ">".
Note that many of these arrows, including some pairs with one left arrow and one right arrow, are 
overlapping.

1)
"<<<<<<<<<<"

Returns: 1

All arrows are of length 1. Note that "<" is both a left single arrow and a left double arrow 
according to the definition.

2)
"----==-"

Returns: -1

No arrows contained.

3)
"<----=====>"

Returns: 6



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