n = int(input())
s = input().strip()

prefixes = []
for i in range(n):
    prefix = s[:i+1]
    l = prefix.count('(')
    r = len(prefix) - l
    balance = l - r
    prefixes.append((balance, prefix))

# Sort the prefixes in descending order of balance
prefixes.sort(reverse=True, key=lambda x: x[0])

current_left = 0
total_pairs = 0

for balance, prefix in prefixes:
    for c in prefix:
        if c == '(':
            current_left += 1
        else:
            if current_left > 0:
                current_left -= 1
                total_pairs += 1

print(total_pairs * 2)