package MaximiseSum;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.PrintWriter;

import java.util.Arrays;

import java.util.Scanner;

import java.util.TreeSet;

/**

* Created by Daniel on 26/10/15.

*/

public class Solution {

/**

* Balanced Binary Search Tree (ADT)

*

* Java notice:

* 1. modulo can return negaitve

* 2. prefer long over int

*/

long solve(long N, long M, long[] A) {

if (N != A.length)

System.exit(1);

long s = 0;

TreeSet<Long> ts = new TreeSet<>();

long maxa = 0;

for(long a: A) {

s = (s+a)%M;

long upper = s;

try { upper = ts.ceiling(s+1); }

catch (NullPointerException e) {}

maxa = Math.max(maxa, Math.max(s, (s-upper+M)%M));

ts.add(s);

}

return maxa;

}

public static void main(String[] args) throws FileNotFoundException {

Solution solution = new Solution();

Scanner in = new Scanner(new File("java/src/0.in"));

// Scanner in = new Scanner(System.in);

PrintWriter out = new PrintWriter(System.out);

int T = Integer.valueOf(in.nextLine());

for (int i = 0; i < T; i++) {

long[] NM = Arrays.stream(in.nextLine().split(" ")).mapToLong(Long::valueOf).toArray();

long[] A = Arrays.stream(in.nextLine().split(" ")).mapToLong(Long::valueOf).toArray();

out.println(solution.solve(NM[0], NM[1], A));

}

out.flush();

}

}