#include <bits/stdc++.h>
using namespace std;
int arr[100000];
int pre[100000];
int leftMax;
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  int t;
  cin >> t;
  while (t--) {
    int maxLen = 0;
    int n, x;
    cin >> n >> x;
    for (int i = 0; i < n; i++) cin >> arr[i];
    pre[0] = arr[0];
    for (int i = 1; i < n; i++) pre[i] = arr[i] + pre[i - 1];
    leftMax = -1;
    for (int i = 0; i < n; i++) {
      pre[i] = pre[i] % x;
      if (pre[i] != 0) maxLen = i + 1;
      if (pre[i] != 0 && leftMax == -1) leftMax = i;
    }
    if (maxLen == 0)
      cout << "-1\n";
    else {
      int finalLen = maxLen;
      for (int i = 0; i < n; i++) {
        if (pre[i] == 0)
          finalLen = max(finalLen, max(abs(i - leftMax), abs(i - maxLen)));
      }
      cout << finalLen << "\n";
    }
  }
  return 0;
}
