n = int(input())
s = input().strip()
c = ""
for i in range(n):
    c += s[i]
    if s[i:i+2] == "()":
        c += "1"
    if s[i:i+2] == ")(":
        c += "*"
    if s[i:i+2] == "))":
        c += "+1"
print(eval(c))