N = int(input())
brace = input().strip()
exp = ''
for i in range(N - 1):
    exp += brace[i]
    if brace[i] == ')' and brace[i + 1] == '(':
        exp += '*'
    elif brace[i] == '(' and brace[i + 1] == ')':
        exp += '1'
    elif brace[i] == ')' and brace[i + 1] == ')':
        exp += '+1'
exp += ')'

#print(exp)
print(eval(exp))