#include <bits/stdc++.h>
using namespace std;
long long power(long long a, long long b) {
  if (b == 0) return 1;
  if (b == 1) return a;
  long long r = power(a, b / 2);
  r = r * r;
  if (b % 2 == 0)
    return r;
  else
    return r * a;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t, n, x, i, sum, sum1;
  cin >> t;
  while (t--) {
    long long k = 0, ans = INT_MIN;
    sum = 0, sum1 = 0;
    cin >> n >> x;
    long long arr[n];
    for (i = 0; i < n; i++) {
      cin >> arr[i];
      sum += arr[i];
      if (arr[i] % x == 0) k++;
    }
    if (k == n)
      cout << -1 << endl;
    else if (sum % x != 0)
      cout << n << endl;
    else {
      sum1 = sum;
      for (i = 0; i < n; i++) {
        sum1 -= arr[i];
        if (sum1 % x != 0) {
          ans = max(ans, (n - i - 1));
          break;
        }
      }
      sum1 = sum;
      for (i = n - 1; i >= 0; i--) {
        sum1 -= arr[i];
        if (sum1 % x != 0) {
          ans = max(ans, i);
          break;
        }
      }
      cout << ans << endl;
    }
  }
  return 0;
}
