write a go solution for Description:
Mircea has n pictures. The i-th picture is a square with a side length of s_i centimeters.

He mounted each picture on a square piece of cardboard so that each picture has a border of w centimeters of cardboard on all sides. In total, he used c square centimeters of cardboard. Given the picture sizes and the value c, can you find the value of w?

A picture of the first test case. Here c=50=5^2+4^2+3^2, so w=1 is the answer.

Please note that the piece of cardboard goes behind each picture, not just the border.

Input Format:
The first line contains a single integer t (1<=t<=1000) — the number of test cases.

The first line of each test case contains two positive integers n (1<=n<=2*10^5) and c (1<=c<=10^18) — the number of paintings, and the amount of used square centimeters of cardboard.

The second line of each test case contains n space-separated integers s_i (1<=s_i<=10^4) — the sizes of the paintings.

The sum of n over all test cases doesn't exceed 2*10^5.

Additional constraint on the input: Such an integer w exists for each test case.

Please note, that some of the input for some test cases won't fit into 32-bit integer type, so you should use at least 64-bit integer type in your programming language (like long long for C++).

Output Format:
For each test case, output a single integer — the value of w (w>=1) which was used to use exactly c squared centimeters of cardboard.

Note:
The first test case is explained in the statement.

For the second test case, the chosen w was 2, thus the only cardboard covers an area of c=(2*2+6)^2=10^2=100 squared centimeters.

For the third test case, the chosen w was 4, which obtains the covered area c=(2*4+2)^2x5=10^2x5=100x5=500 squared centimeters.. Output only the code with no comments, explanation, or additional text.