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문제

The world should be finely balanced. Positive vs. negative, light vs. shadow, and left vs. right brackets. Your mission is to write a program that judges whether a string is balanced with respect to brackets so that we can observe the balance of the world.

A string that will be given to the program may have two kinds of brackets, round (“( )”) and square (“[ ]”). A string is balanced if and only if the following conditions hold.

  • For every left round bracket (“(”), there is a corresponding right round bracket (“)”) in the following part of the string.
  • For every left square bracket (“[”), there is a corresponding right square bracket (“]”) in the following part of the string.
  • For every right bracket, there is a left bracket corresponding to it.
  • Correspondences of brackets have to be one to one, that is, a single bracket never corresponds to two or more brackets.
  • For every pair of corresponding left and right brackets, the substring between them is balanced.

입력

The input consists of one or more lines, each of which being a dataset. A dataset is a string that consists of English alphabets, space characters, and two kinds of brackets, round (“( )”) and square (“[ ]”), terminated by a period. You can assume that every line has 100 characters or less. The line formed by a single period indicates the end of the input, which is not a dataset.

출력

For each dataset, output “yes” if the string is balanced, or “no” otherwise, in a line. There may not be any extra characters in the output.

예제 입력

So when I die (the [first] I will see in (heaven) is a score list).
[ first in ] ( first out ).
Half Moon tonight (At least it is better than no Moon at all].
A rope may form )( a trail in a maze.
Help( I[m being held prisoner in a fortune cookie factory)].
([ (([( [ ] ) ( ) (( ))] )) ]).
 .
.

예제 출력

yes
yes
no
no
no
yes
yes

힌트