description: You are given n integers a_1, a_2, …, a_n. Find the maximum value of max(a_l, a_{l + 1}, …, a_r) ⋅ min(a_l, a_{l + 1}, …, a_r) over all pairs (l, r) of integers for which 1 ≤ l < r ≤ n.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10 000) — the number of test cases.
  
  The first line of each test case contains a single integer n (2 ≤ n ≤ 10^5).
  
  The second line of each test case contains n integers a_1, a_2, …, a_n (1 ≤ a_i ≤ 10^6).
  
  It is guaranteed that the sum of n over all test cases doesn't exceed 3 ⋅ 10^5.
  
  Output
  
  For each test case, print a single integer — the maximum possible value of the product from the statement.
  
  Example
  
  Input
  
  
  4
  3
  2 4 3
  4
  3 2 3 1
  2
  69 69
  6
  719313 273225 402638 473783 804745 323328
  
  
  Output
  
  
  12
  6
  4761
  381274500335
  
  Note
  
  Let f(l, r) = max(a_l, a_{l + 1}, …, a_r) ⋅ min(a_l, a_{l + 1}, …, a_r).
  
  In the first test case, 
  
    * f(1, 2) = max(a_1, a_2) ⋅ min(a_1, a_2) = max(2, 4) ⋅ min(2, 4) = 4 ⋅ 2 = 8. 
    * f(1, 3) = max(a_1, a_2, a_3) ⋅ min(a_1, a_2, a_3) = max(2, 4, 3) ⋅ min(2, 4, 3) = 4 ⋅ 2 = 8. 
    * f(2, 3) = max(a_2, a_3) ⋅ min(a_2, a_3) = max(4, 3) ⋅ min(4, 3) = 4 ⋅ 3 = 12. 
  
  
  
  So the maximum is f(2, 3) = 12.
  
  In the second test case, the maximum is f(1, 2) = f(1, 3) = f(2, 3) = 6.
solution: import javax.swing.*;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class A {
      static ArrayList<Integer> [] adj;
      static ArrayList<Integer> temp;
      static int mod = (int) 1e9+7;
      static boolean[] vis = new boolean[(int)1e5];
  
      public static void main(String[] args) throws IOException {
          FastScanner s=new FastScanner();
          int t = s.nextInt();
  //        int t = 1;
          while(t-->0){
              int n = s.nextInt();
              int[] a = s.readArray(n);
              int[] max = new int[n];
              int[] min = new int[n];
              int[] max1 = new int[n];
              int[] min1 = new int[n];
              max[0] = a[0];
              min[0] = a[0];
              long ans=0;
              for(int i=1;i<n;i++){
                  max[i] = Math.max(max[i-1],a[i]);
                  min[i] = Math.min(min[i-1],a[i]);
                  ans = Math.max(ans,max[i]*(long)min[i]);
              }
              max1[n-1]=a[n-1];
              min1[n-1]=a[n-1];
              for(int i=n-1;i>0;i--){
                  max1[i] = Math.max(max1[i-1],a[i]);
                  min1[i] = Math.min(min1[i-1],a[i]);
                  ans = Math.max(ans,max1[i]*(long)min1[i]);
              }
              for(int i=1;i<n;i++){
                  ans=Math.max(a[i]*(long)a[i-1],ans);
              }
              System.out.println(ans);
          }
      }
  //Important
  //Dont't stick on same approach
  //Check long
  
  
  
  
      static void dfs(int i){
          vis[i]=true;
          temp.add(i);
          List<Integer> Y = adj[i];
          for(int x:Y){
              if(!vis[x])dfs(x);
          }
      }
  
      static long gcd(long a, long b) throws IOException {
          return (b == 0) ? a : gcd(b, a % b);
      }
  
      static int gcd(int a, int b) throws IOException {
          return (b == 0) ? a : gcd(b, a % b);
      }
  
      static void sortr(int[] a) {
          ArrayList<Integer> l = new ArrayList<>();
          for (int i : a)
              l.add(i);
          Collections.sort(l, Collections.reverseOrder());
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static void sort(int[] a) {
          ArrayList<Integer> l = new ArrayList<>();
          for (int i : a)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static void sort(long[] a) {
          ArrayList<Long> l = new ArrayList<>();
          for (long i : a)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < a.length; i++)
              a[i] = l.get(i);
      }
  
      static class FastScanner {
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st = new StringTokenizer("");
  
          String next() {
              while (!st.hasMoreTokens())
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          int[] readArray(int n) {
              int[] a = new int[n];
              for (int i = 0; i < n; i++)
                  a[i] = nextInt();
              return a;
          }
          long nextLong() {
              return Long.parseLong(next());
          }
      }
  }