There is a sequence of
n+2 elements a0, a1,…, an+1
(n <= 3000; -1000 <=
ai 1000). It is known that ai
= (ai–1 + ai+1)/2 – ci for each i=1, 2, ..., n. You are given a0, an+1,
c1, ... , cn. Write a program which calculates a1.
The first line is the number of test cases, followed by a blank line.
For each test case, the first line of an input file contains an integer n.
The next two lines consist of numbers a0 and an+1 each
having two digits after decimal point, and the next n lines contain numbers ci
(also with two digits after decimal point), one number per line.
Each test case will be separated by a single line.
The Output
For each test case, the output file should contain a1 in the
same format as a0 and an+1.
Print a blank line between the outputs for two consecutive test cases.
Sample Input
1
1
50.50
25.50
10.15
27.85