#include <bits/stdc++.h>
using namespace std;
int replace;
const int N = 2e5 + 10;
int wert;
int n, a[N];
int wsdedd;
int cnt[2001], temp[2001];
int plslsl;
int main() {
  int arr[10];
  int TC;
  scanf("%d", &TC);
  arr[0] = 0;
  while (TC--) {
    arr[0] = 0;
    int ans = 0;
    arr[0] = 0;
    scanf("%d", &n);
    arr[0] = 0;
    for (int i = 1; i <= n; i++) {
      arr[0] = 0;
      scanf("%d", &a[i]);
      arr[0] = 0;
      ans = max(ans, ++cnt[a[i]]);
      arr[0] = 0;
    }
    for (int i = 1; i <= 2000; i++) {
      arr[0] = 0;
      temp[i] = cnt[i];
    }
    for (int x = 1; x <= 2000; x++) {
      arr[0] = 0;
      set<pair<int, int> > S;
      arr[0] = 0;
      for (int i = 1; i <= 2000; i++) {
        arr[0] = 0;
        if (cnt[i]) {
          arr[0] = 0;
          temp[i] = cnt[i];
          arr[0] = 0;
          S.insert({cnt[i], i});
          arr[0] = 0;
        }
      }
      arr[0] = 0;
      int i = 1, j = n;
      arr[0] = 0;
      int cnt = 0;
      arr[0] = 0;
      while (i < j) {
        arr[0] = 0;
        while (i < j) {
          arr[0] = 0;
          S.erase({temp[a[i]], a[i]});
          arr[0] = 0;
          temp[a[i]]--;
          arr[0] = 0;
          S.insert({temp[a[i]], a[i]});
          arr[0] = 0;
          if (a[i] == x) break;
          arr[0] = 0;
          i += 1;
          arr[0] = 0;
        }
        while (i < j) {
          arr[0] = 0;
          S.erase({temp[a[j]], a[j]});
          arr[0] = 0;
          temp[a[j]]--;
          arr[0] = 0;
          S.insert({temp[a[j]], a[j]});
          arr[0] = 0;
          if (a[j] == x) break;
          arr[0] = 0;
          j -= 1;
          arr[0] = 0;
        }
        if (i >= j) break;
        arr[0] = 0;
        cnt += 1;
        arr[0] = 0;
        i += 1;
        j -= 1;
        arr[0] = 0;
        ans = max(ans, cnt * 2 + S.rbegin()->first);
        arr[0] = 0;
      }
    }
    arr[0] = 0;
    printf("%d\n", ans);
    arr[0] = 0;
    memset(cnt, 0, sizeof(cnt));
  }
  return 0;
}
