input()
seq = input()

prev = ''

string = []

for i in seq:
    if prev == '(' and i == ')':
        string.append('1')
    elif prev == ')':
        if i == '(':
            string.append('*')
        else:
            string.append('+1')
    string.append(i)
    prev = i

string = ''.join(string)
print(eval(string))