'''
Online Python Interpreter.
Code, Compile, Run and Debug python program online.
Write your code in this editor and press "Run" button to execute it.
'''
import re
pattern = '\[%clk ([^\]]+)'
test_string = 'blah blah [%clk 1:05:23] blah blah'
print(re.search(pattern, test_string).group(1))