N = int(input())
S = input()

temp = S[0]
last = S[0]

for ix, ch in enumerate(S):
    if ix == 0:
        continue

    if last == ')' and ch == '(':
        temp += '*('
        last = ch
        continue

    if last == '(' and ch == ')':
        temp += '1)'
        last = ch
        continue

    if last == ')' and ch == ')':
        temp += '+1)'
        last = ch
        continue

    temp += ch

print(eval(temp))