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

prefixes = []
for i in range(n):
    substr = s[:i+1]
    a = substr.count('(')
    b = substr.count(')')
    prefixes.append((a - b, substr))

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

balance = 0
result = 0

for _, substr in prefixes:
    for c in substr:
        if c == '(':
            balance += 1
        else:
            if balance > 0:
                result += 2
                balance -= 1

print(result)