num = input()
tmp = input().strip()

res = []

for i in range(len(tmp)-1):
        res.append(tmp[i])
        if tmp[i] == ')' and tmp[i+1] == '(':
                res.append('+')
        elif tmp[i] == '(' and tmp[i+1] == ')':
                res.append('1')
        elif tmp[i] == ')' and tmp[i+1] == ')':        
                res.append('+')
                res.append('1')
        else:
                continue
res.append(')')
print(eval("".join(res)))