This is yet another problem dealing with regular bracket sequences.

We should remind you that a bracket sequence is called regular, if by inserting «+» and «1» into it we can get a correct mathematical expression. For example, sequences «(())()», «()» and «(()(()))» are regular, while «)(», «(()» and «(()))(» are not. 

You are given a string of «(» and «)» characters. You are to find its longest substring that is a regular bracket sequence. You are to find the number of such substrings as well.
The first line of the input file contains a non-empty string, consisting of «(» and «)» characters. Its length does not exceed 10<sup class="upper-index">6</sup>.
#!/usr/bin/env python


def main():
    longest = 0
    count = 1
    unbalanced = list()
    push = unbalanced.append
    pop = unbalanced.pop
    head = -1
    for cursor, paren in enumerate(input()):
        if paren == "(":
            push(cursor)
        elif unbalanced:
            pop()
            span = cursor - (unbalanced[-1] if unbalanced else head)
            if span == longest:
                count += 1
            elif span > longest:
                longest = span
                count = 1
        else:
            head = cursor
    print(longest, count)


if __name__ == '__main__':
    main()
