#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n + 5];
    for (int i = 0; i < n; i++) cin >> a[i];
    int ans = 1;
    for (int i = 1; i <= 26; i++) {
      int x = 1;
      while (true) {
        int count = 0;
        int j, k;
        for (j = 0; j < n; j++) {
          if (a[j] == i) count++;
          if (count == x) break;
        }
        int count1 = 0;
        for (k = n - 1; k >= 0; k--) {
          if (a[k] == i) count1++;
          if (count1 == x) break;
        }
        if (j == n || k == -1) break;
        if (j >= k) break;
        vector<int> freq;
        for (int l = 0; l <= 27; l++) freq.push_back(0);
        for (int l = j + 1; l < k; l++) freq[a[l]]++;
        int y = 0;
        for (int l = 0; l <= 26; l++) y = max(y, freq[l]);
        ans = max(ans, 2 * x + y);
        x++;
      }
    }
    cout << ans << '\n';
  }
  return 0;
}
