input()
ret = 0
last, *data = input()
new_string = [last]
for c in data:
  q = last + c
  if q == ')(':
    new_string.append('*')
  elif q == '()':
    new_string.append('1')
  elif q == '))':
    new_string.append('+1')
  last = c
  new_string.append(c)
print(eval(''.join(new_string)))