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 java.io.*;
  import java.math.*;
  import java.util.*;
  
  public class Main {
  
      static final int MAX_N = 1000010;
      static final int INF = 0x3f3f3f3f;
      static final int mod = 1000000007;
  
  
      public static void main(String[] args) throws IOException {
          initReader(System.in);
  
  
          int T = nextInt();
          for (int i = 1; i <= T; i++)
          solve();
  
  
          pw.flush();
      }
  
  
      /*******************************************************************************************************************************/
  
      public static void solve() throws IOException {
          int n = nextInt();
  
          long[] a = new long[n];
  
          for (int i = 0; i < n; i++) a[i] = nextLong();
  
          long ans = -INF;
          for (int i = 1; i < n; i++) ans = Math.max(ans, a[i] * a[i - 1]);
  
          pw.println(ans);
      }
  
      /*******************************************************************************************************************************/
  
  
      /*******************************************************************************************************************************/
  
      static BufferedReader reader;
      static StringTokenizer tokenizer;
      static PrintWriter pw;
  
      public static void initReader(InputStream input) throws IOException {
          reader = new BufferedReader(new InputStreamReader(input));
          tokenizer = new StringTokenizer("");
          pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
  
  //        reader = new BufferedReader(new FileReader("test.in"));
  //        tokenizer = new StringTokenizer("");
  //        pw = new PrintWriter(new BufferedWriter(new FileWriter("test1.out")));
      }
  
      public static boolean hasNext() {
          try {
              while (!tokenizer.hasMoreTokens()) {
                  tokenizer = new StringTokenizer(reader.readLine());
              }
          } catch (Exception e) {
              return false;
          }
          return true;
      }
  
      public static String next() throws IOException {
          while (!tokenizer.hasMoreTokens()) {
              tokenizer = new StringTokenizer(reader.readLine());
          }
          return tokenizer.nextToken();
      }
  
      public static String nextLine() {
          try {
              return reader.readLine();
          } catch (Exception e) {
              return null;
          }
      }
  
      public static int nextInt() throws IOException {
          return Integer.parseInt(next());
      }
  
      public static long nextLong() throws IOException {
          return Long.parseLong(next());
      }
  
      public static double nextDouble() throws IOException {
          return Double.parseDouble(next());
      }
  
      public static char nextChar() throws IOException {
          return next().charAt(0);
      }
  
      public static short nextShort() throws IOException {
          return Short.parseShort(next());
      }
  
  }
  
  