from lib import *

data = open(0).read()

part_2 = True

floor = 0
for i, c in enumerate(data):
    if c == "(":
        floor += 1
    elif c == ")":
        floor -= 1
    else:
        print(c)
        assert False

    if part_2 and floor == -1:
        print(i + 1)
        break

if not part_2:
    print(floor)