# () adds 1, )) adds 1, )( multiplies the operands on both sides (*)

def solve(expr):
    parts = list(expr)
    evaluated = ""
    for i in range(len(parts)-1):
        currchar, nextchar = parts[i], parts[i+1]
        if currchar == "(" and nextchar == ")":
            evaluated += currchar + "1"
        elif currchar == ")" and nextchar == ")":
            evaluated += currchar + "+1"
        elif currchar == ")" and nextchar == "(":
            evaluated += currchar + "*"
        else:
            evaluated += currchar
    evaluated += parts[-1]
    return eval(evaluated)
N = int(input())
expr = input()
print(solve(expr))