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.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.io.PrintStream;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   *
   * @author sarthakmanna
   */
  public class Main {
      public static void main(String[] args) {
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          FastReader in = new FastReader(inputStream);
          PrintWriter out = new PrintWriter(outputStream);
          ACherry solver = new ACherry();
          int testCount = Integer.parseInt(in.next());
          for (int i = 1; i <= testCount; i++)
              solver.solve(i, in, out);
          out.close();
      }
  
      static class ACherry {
          public void solve(int testNumber, FastReader in, PrintWriter out) {
              int i, j, k;
  
              int N = in.nextInt();
              long[] A = in.getLongArray(N);
  
              long ans = 0;
              for (i = 1; i < N; ++i) ans = Math.max(ans, A[i - 1] * A[i]);
              out.println(ans);
          }
  
      }
  
      static class FastReader {
          static final int BUFSIZE = 1 << 20;
          static byte[] buf;
          static int index;
          static int total;
          static InputStream in;
  
          public FastReader(InputStream is) {
              try {
                  in = is;
                  buf = new byte[BUFSIZE];
              } catch (Exception e) {
              }
          }
  
          private int scan() {
              try {
                  if (index >= total) {
                      index = 0;
                      total = in.read(buf);
                      if (total <= 0)
                          return -1;
                  }
                  return buf[index++];
              } catch (Exception | Error e) {
                  System.err.println(e.getMessage());
                  return 13 / 0;
              }
          }
  
          public String next() {
              int c;
              for (c = scan(); c <= 32; c = scan()) ;
              StringBuilder sb = new StringBuilder();
              for (; c > 32; c = scan())
                  sb.append((char) c);
              return sb.toString();
          }
  
          public int nextInt() {
              int c, val = 0;
              for (c = scan(); c <= 32; c = scan()) ;
              boolean neg = c == '-';
              if (c == '-' || c == '+')
                  c = scan();
              for (; c >= '0' && c <= '9'; c = scan())
                  val = (val << 3) + (val << 1) + (c & 15);
              return neg ? -val : val;
          }
  
          public long nextLong() {
              int c;
              long val = 0;
              for (c = scan(); c <= 32; c = scan()) ;
              boolean neg = c == '-';
              if (c == '-' || c == '+')
                  c = scan();
              for (; c >= '0' && c <= '9'; c = scan())
                  val = (val << 3) + (val << 1) + (c & 15);
              return neg ? -val : val;
          }
  
          public long[] getLongArray(int size) {
              long[] ar = new long[size];
              for (int i = 0; i < size; ++i) ar[i] = nextLong();
              return ar;
          }
  
      }
  }
  
  