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A8038. Three Base Stations

编程题 普及/提高-

题目描述

The New Vasjuki village is stretched along the motorway and that's why every house on it is characterized by its shift relative to some fixed point — the $x_{i}$ coordinate. The village consists of $n$ houses, the $i$ -th house is located in the point with coordinates of $x_{i}$ .

TELE3, a cellular communication provider planned to locate three base stations so as to provide every house in the village with cellular communication. The base station having power $d$ located in the point $t$ provides with communication all the houses on the segment $[t-d,t+d]$ (including boundaries).

To simplify the integration (and simply not to mix anything up) all the three stations are planned to possess the equal power of $d$ . Which minimal value of $d$ is enough to provide all the houses in the village with cellular communication.

输入格式

The first line contains an integer $n$ ( $1<=n<=2·10^{5}$ ) which represents the number of houses in the village. The second line contains the coordinates of houses — the sequence $x_{1},x_{2},...,x_{n}$ of integer numbers ( $1<=x_{i}<=10^{9}$ ). It is possible that two or more houses are located on one point. The coordinates are given in a arbitrary order.

输出格式

Print the required minimal power $d$ . In the second line print three numbers — the possible coordinates of the base stations' location. Print the coordinates with 6 digits after the decimal point. The positions of the stations can be any from $0$ to $2·10^{9}$ inclusively. It is accepted for the base stations to have matching coordinates. If there are many solutions, print any of them.

输入输出样例

输入 #1
4
1 2 3 4
输出 #1
0.500000
1.500000 2.500000 3.500000
输入 #2
3
10 20 30
输出 #2
0
10.000000 20.000000 30.000000
输入 #3
5
10003 10004 10001 10002 1
输出 #3
0.500000
1.000000 10001.500000 10003.500000
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