Compiler#11252
One of the principles of many compilers is to check that the brackets in the given code open and close in the correct order. To check this in a code snippet, you first need to remove characters other than brackets, that is, to get a string consisting only of brackets. Then the correctness of the bracket sequence in this string can be checked using the data structure "stack".
For example: For the given string "for(){inta[]if(){}else{}}", the answer will be the string "(){[](){}{}}". To simplify, the string may contain only lowercase and uppercase Latin letters, digits from to and (){} — types of brackets.
A single string is given (2 \leq |S| \leq 1000, where denotes the length of the string , consists only of lowercase and uppercase Latin letters, digits from to and (){} — types of brackets).
After removing the characters other than brackets, specify the resulting string.
Example 1
Example 2
Example 3
The first example is explained above in the condition.
In the third example, due to the absence of brackets, the answer will be empty.
In this task, points are awarded for each correct test. The maximum number of points is . Examples are not included in system tests.