n = int(input())
st = input()

ans = ""
ans += st[0]
for i in range(1, n):
	if st[i - 1] == ')' and st[i] == '(':
		ans += "*"
	if st[i - 1] == '(' and st[i] == ')':
		ans += "1"
	if st[i - 1] == ')' and st[i] == ')':
		ans += "+1"
	ans += st[i]

print(eval(ans))