from copy import copy


def main():
    n = int(input())
    last, current = 0, 0
    rez = 0
    for i, elem in enumerate(input()[:]):
        last = copy(current)
        current = elem
        if i == 0:
            continue

        if current == last == ")" or (current == ")" and last == "("):
            rez += 1

    return rez