A row of tiles is given as a string of lowercase English letters. Whenever two adjacent tiles show the same letter, that pair is removed together, and the tiles on either side become adjacent (and may then form a new removable pair). Keep removing adjacent equal pairs until no two adjacent tiles are equal. The final string is unique regardless of the order in which pairs are removed.
Print the final string. If every tile is removed, print an empty line.
Input format
Line 1: a string of lowercase English letters.
Output format
A single line: the final string after all adjacent equal pairs have been removed (an empty line if nothing remains).
Constraints
- 1 <= length of the string <= 100000
- The string contains only lowercase English letters.