Hi, Is it possible to get one more expression from extended in order to check why code fail with ex. I have checked all combinations that i could imagine and my code works fine for me. Maybe any additional rules should be followed? I have checked the following strings '{(asda)})sd[s]d' == 'Correct expression' '({a})' == 'Incorrect expression' '()(({a}))' == 'Correct expression' '](d)[({)}]' == 'Incorrect expression' and many other combinations