tijie

#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int n;
    cin >> n;
    while (n--){
        int k;
        cin >> k;
        long long arr[k];
        for(int i = 0; i < k; i++){
            cin >> arr[i];
        }sort(arr, arr + k);
        bool flag = true;
        for (int i = 1; i < k - 1; i++){
            if (arr[i] == arr[i - 1] || arr[i] == arr[i + 1]){
                flag = false;
            }
        }
        if (!flag) cout << "NO" << endl;
        else cout << "YES"<< endl;
    }
    return 0;
}