#include <bits/stdc++.h>
using namespace std;
long long dec(long long x) {
  while (x != 0) {
    long long no = x % 10;
    x = x / 10;
    if (no == 7) {
      return 1;
    }
  }
  return 0;
}
long long oct(long long x) {
  while (x != 0) {
    long long no = x % 8;
    x = x / 8;
    if (no == 7) {
      return 1;
    }
  }
  return 0;
}
int main() {
  long long i, j;
  long long Tc, l = 1;
  cin >> Tc;
  while (Tc--) {
    long long n, k;
    cin >> n >> k;
    long long a[n], s = 0, ses = 0;
    for (i = 1; i <= n; i++) {
      cin >> a[i];
      s += a[i];
      if (a[i] % k == 0) ses++;
    }
    if (s % k != 0)
      cout << n << endl;
    else if (ses == n)
      cout << -1 << endl;
    else {
      long long l = 0, r = 0;
      for (i = 1; i <= n; i++) {
        if (a[i] % k != 0) {
          l = i;
          break;
        }
      }
      for (i = n; i > 0; i--) {
        if (a[i] % k != 0) {
          r = i;
          break;
        }
      }
      long long p = max(l, n - l);
      long long q = max(n - r + 1, r - 1);
      long long ans = max(p, q);
      cout << ans << endl;
    }
  }
  return 0;
}
