/*
*/

//#pragma comment(linker, "/STACK:16777216")
#include <fstream>
#include <iostream>
#include <string>
#include <complex>
#include <math.h>
#include <set>
#include <vector>
#include <map>
#include <queue>
#include <stdio.h>
#include <stack>
#include <algorithm>
#include <list>
#include <ctime>
#include <memory.h>
#include <ctime>

#define y0 sdkfaslhagaklsldk
#define y1 aasdfasdfasdf
#define yn askfhwqriuperikldjk
#define j1 assdgsdgasghsf
#define tm sdfjahlfasfh
#define lr asgasgash

#define eps 1e-9
//#define M_PI 3.141592653589793
#define bs 1000000007
#define bsize 256
#define right adsgasgadsg
#define free adsgasdg
#define MAG 10000

using namespace std;

long long tests,n,m,s,q,val,ans;
set<long long> S;
set<long long>::iterator it;

int main(){
//freopen("hiking.in","r",stdin);
//freopen("hiking.out","w",stdout);
//freopen("C:/input.txt","r",stdin);
//freopen("C:/output.txt","w",stdout);
ios_base::sync_with_stdio(0);
//cin.tie(0);

cin>>tests;
for (;tests;--tests)
{
 cin>>n>>m;
 S.clear();
 s=0;
 S.insert(0);
 S.insert(m);
 ans=0;
 for (int i=1;i<=n;i++)
 {
  cin>>q;
  s+=q;
  s%=m;
  it=S.lower_bound(s);
  if ((*it)==s)++it;

   val=(*it);
   ans=max(ans,(m+s-val)%m);
   //cout<<s<<"   "<<val<<endl;
  S.insert(s);
  S.insert(s+m);
 }
 cout<<ans<<endl;
}

cin.get();cin.get();
return 0;}