#to check wheather the given parenthesis are valid  or not implementation is done using stack
pat = '[({()})[]}'
lst = []
srt_pat = ['{', '(', '[']
cls_pat = ['}', ')', ']']
chec_lst=['{}','()','[]']
for i in range(len(pat)):
    if (pat[i] in srt_pat):
        lst.append(pat[i])
    else:
        x=lst[-1]+pat[i]
        if (x in chec_lst):
            lst.pop()
        else:
            print('not valid pat')
            break
print(lst)
if (len(lst) == 0):
    print('valid pat')