write a go solution for Description:
n students are taking an exam. The highest possible score at this exam is m. Let a_i be the score of the i-th student. You have access to the school database which stores the results of all students.

You can change each student's score as long as the following conditions are satisfied:

- All scores are integers
- 0<=a_i<=m
- The average score of the class doesn't change.

You are student 1 and you would like to maximize your own score.

Find the highest possible score you can assign to yourself such that all conditions are satisfied.

Input Format:
Each test contains multiple test cases.

The first line contains the number of test cases t (1<=t<=200). The description of the test cases follows.

The first line of each test case contains two integers n and m (1<=n<=10^3, 1<=m<=10^5)  — the number of students and the highest possible score respectively.

The second line of each testcase contains n integers a_1,a_2,...,a_n (0<=a_i<=m)  — scores of the students.

Output Format:
For each testcase, output one integer  — the highest possible score you can assign to yourself such that both conditions are satisfied._

Note:
In the first case, a=[1,2,3,4], with average of 2.5. You can change array a to [10,0,0,0]. Average remains 2.5, and all conditions are satisfied.

In the second case, 0<=a_i<=5. You can change a to [5,1,1,3]. You cannot increase a_1 further as it will violate condition 0<=a_i<=m.. Output only the code with no comments, explanation, or additional text.