A codility challenge to detect if brackets are properly nested

A string S consisting of N characters is called properly nested if:

S is empty; S has the form "(U)" where U is a properly nested string; S has the form "VW" where V and W are properly nested strings. For example, string "(()(())())" is properly nested but string "())" isn't.

Write a function:

def solution(s) that, given a string S consisting of N characters, returns 1 if string S is properly nested and 0 otherwise.

For example, given S = "(()(())())", the function should return 1 and given S = "())", the function should return 0, as explained above.

Assume that:

N is an integer within the range [0..1,000,000]; string S consists only of the characters "(" and/or ")". Complexity:

expected worst-case time complexity is O(N); expected worst-case space complexity is O(1) (not counting the storage required for input arguments).