Write a program that takes an undefined number of `string` in arguments. For each argument, if the expression is correctly bracketed, the program prints on the standard output `OK` followed by a newline (`'\n'`), otherwise it prints `Error` followed by a newline.
Symbols considered as brackets are parentheses `(` and `)`, square brackets `[` and `]` and curly braces `{` and `}`. Every other symbols are simply ignored.
An opening bracket must always be closed by the good closing bracket in the correct order. A `string` which does not contain any bracket is considered as a correctly bracketed `string`.
