﻿ Fuzhou University OnlineJudge ﻿  Problem 1602 Best results

## Problem Description

CET is short for “College English Test”. Oaiei is an outstanding student, and he will participate in CET6 to test his English proficiency every year. This year's examination he wants to have a fun, with his own level to the test each time, he almost gets the same results. So he wants to guess the answer this time. The multiple-choice questions of CET have four options, and you should select a correct answer to the question. For each choice he has a probability to select the correct answer. Now the question comes, give you the probability that oaiei will select the correct answer and output the probability that he will get full mark.

## Input

There are multiple tests. For each test, the first line is a positive number N (1<=N<=100); N is the number of multiple-choice questions. The following N lines, each line is a percentage, the percentage is in the form of m% (m is a positive integer and 1<=m<=100), represents the probability oaiei can select the correct answer and he can not guess the all questions with the probability of 100%.

## Output

Output the exact value of the probability that oaiei can get full mark. The output value should be accuracy that is to say you should output the probability’s precise decimal and insignificant trailing zeros must not be printed..

4 7% 30% 40% 14%

0.001176

## Source

FOJ月赛-2008年5月

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