#!python
# -*- coding: utf-8 -*-

N = int(input())
S = input()

R = 0
L = 0
for i, c in enumerate(S):
    if c == '(':
        L += len(S) - i
    else:
        R += len(S) - i
if S[0] == ')':
    print(min(R, L) * 2 - 2)
else:
    print(min(R, L) * 2)