E-Prof. Slim

////////////////          PRANTA KUMER PANDIT            ///////////////
//                      Test Case Less Template                       ||
//                                                                    ||
//                                                                    ||
//      BANGLADESH  UNIVERSITY OF BUSINESS AND TECHNOLOGY             ||
//                          INTAKE 52                                 ||
//                      DEPARTMENT OF CSE                             ||
//                                                                    ||
//||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
//                      So, WELCOME TO ISHAN'S PERADISE           //
//                (-.-) Want to be a Secret tool of next ICPC��(-.-)����//
 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb   push_back
#define yes   cout<<"YES"<<endl
#define no   cout<<"NO"<<endl
#define all(x) (x).begin(), (x).end()
#define    gcd(a,b)      __gcd(a,b)
#define    lcm(a,b)  (a*b)/__gcd(a,b)
#define optimize() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//void solve(){
bool cnt(const vector<int>& v) {
    for (int i = 1; i < v.size(); i++) {
        if (v[i] <v[i - 1]) return false;
    }
    return true;
}
int32_t main()
{
    optimize();
int lol;
      cin >> lol;
    while (lol--) {
   // solve();
   int n;
        cin >> n;
        vector<int> a(n), p, ishan;
        for (int i = 0; i < n; ++i) {
            cin >> a[i];
            if (a[i] > 0)
                p.push_back(a[i]);
            else
                ishan.push_back(a[i]);
        }
        if (cnt(p) && cnt(ishan)) {
           yes;
        } else {
           no;
        }
    }
    return 0;
     }
//                                   THANKS������������   ��������������//