N = int(input())

line = input()

exp = ""

i = 0
while True:
    if i <= N-2:
        if line[i:i+2] == '((':
            exp += '('
            i += 1
        elif line[i:i+2] == '()':
            exp += '(1'
            i += 1
        elif line[i:i+2] == '))':
            exp += ')+1'
            i += 1
        elif line[i:i+2] == ')(':
            exp += ')*'
            i += 1
        else:
            pass
    if i == N-1:
        exp += ')'
        break

print(eval(exp))