#include <iostream>
#include<vector>
#include<climits>
using namespace std;
 
int main() {
 int t;
 cin>>t;
  while(t--)
 {
    int n,k;
    cin>>n>>k;
    vector<int>vec(n);
    for (int i = 0; i < n; ++i)
    {
        cin>>vec[i];    }
 
    int ans=INT_MAX;
    for (int i = 0; i < n; ++i)
    {   if(vec[i]%k==0)
        {
        	ans=0;
        	break;
        }
 
    	else
        {ans=min(ans,k-vec[i]%k);}
    }
 
   cout<<ans<<endl;
 
    }
 
    }
 

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15
2 5
7 3
3 3
7 4 1
5 2
9 7 7 3 9
5 5
5 4 1 2 3
7 4
9 5 1 5 9 5 1
3 4
6 3 6
3 4
6 1 5
3 4
1 5 9
4 4
1 4 1 1
3 4
3 5 3
4 5
8 9 9 3
2 5
1 6
2 5
10 10
4 5
1 6 1 1
2 5
7 7