n = int(input())
s = input()

# Preprocess each prefix's L, R, balance, and min_balance
L = []
R = []
balance_list = []
min_balance_list = []

current_L = 0
current_R = 0
balance = 0
min_balance = 0

for c in s:
    if c == '(':
        current_L += 1
        balance += 1
    else:
        current_R += 1
        balance -= 1
    L.append(current_L)
    R.append(current_R)
    balance_list.append(balance)
    min_balance = min(min_balance, balance)
    min_balance_list.append(min_balance)

# Prepare list of prefixes with their min_balance, balance, L, R
prefixes = []
for i in range(n):
    min_b = min_balance_list[i]
    bal = balance_list[i]
    l = L[i]
    r = R[i]
    prefixes.append((min_b, bal, l, r))

# Sort prefixes by min_b descending, then bal descending
prefixes.sort(key=lambda x: (-x[0], -x[1]))

# Process the sorted prefixes to compute global_min and current_balance
current_balance = 0
global_min = 0

for p in prefixes:
    min_b, bal, l, r = p
    new_balance = current_balance + bal
    new_global_min = min(global_min, current_balance + min_b)
    global_min = new_global_min
    current_balance = new_balance

# Compute total_L and total_R
total_L = sum(L)
total_R = sum(R)

# Compute the answer
if global_min >= 0:
    ans = 2 * min(total_L, total_R)
else:
    effective = max(min(total_L, total_R) + global_min, 0)
    ans = 2 * effective

print(ans)