시간 제한메모리 제한제출정답맞힌 사람정답 비율
1 초 128 MB228738.889%

## 문제

Professor Octastichs has invented a new programming language, Smeech. An expression in Smeech may be a positive or negative integer, or may be of the form (p e1 e2) where p is a real number between 0 and 1 (inclusive) and e1 and e2 are Smeech expressions. The value represented by a Smeech expression is as follows:

• An integer represents itself
• With probability p, (p e1 e2) represents x+y where x is the value of e1 and y is the value of e2; otherwise it represents x-y.

Given a Smeech expression, what is its expected value?

## 입력

Input consists of several Smeech expressions, one per line, followed by a line containing ().

## 출력

For each expression, output its expected value to two decimal places.

## 예제 입력 1

7
(.5 3 9)
()


## 예제 출력 1

7.00
3.00