Rookie Mistake

You’re given a string s containing letters of three types, R, B, and ..

R represents your current position, B represents a blocked position, and . represents an empty position. In one step, you can move to any adjacent position to your current position, as long as it is empty. Can you reach either the leftmost position or the rightmost position?

Return true if you can reach either the leftmost or the rightmost position, or false if you cannot.

Constraints

• n ≤ 100,000 where n is the length of s

https://binarysearch.com/problems/Rookie-Mistake

Examples

Example 1

Input

• s = ......B....R..............

Output

• answer = True

Explanation

We can reach the rightmost position since it’s not blocked.

Example 2

Input

• s = B...B...R........BBBB

Output

• answer = False

Explanation

We can’t reach either side since they’re both blocked.

Solution