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.lang.reflect.Array;
  import java.util.*;
  import java.util.function.Predicate;
  
  public class A {
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new
                      InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  
      static FastReader s = new FastReader();
      static PrintWriter out = new PrintWriter(System.out);
  
      private static int[] rai(int n) {
          int[] arr = new int[n];
          for (int i = 0; i < n; i++) {
              arr[i] = s.nextInt();
          }
          return arr;
      }
  
      private static int[][] rai(int n, int m) {
          int[][] arr = new int[n][m];
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < m; j++) {
                  arr[i][j] = s.nextInt();
              }
          }
          return arr;
      }
  
      private static long[] ral(int n) {
          long[] arr = new long[n];
          for (int i = 0; i < n; i++) {
              arr[i] = s.nextLong();
          }
          return arr;
      }
  
      private static long[][] ral(int n, int m) {
          long[][] arr = new long[n][m];
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < m; j++) {
                  arr[i][j] = s.nextLong();
              }
          }
          return arr;
      }
  
      private static int ri() {
          return s.nextInt();
      }
  
      private static long rl() {
          return s.nextLong();
      }
  
      private static String rs() {
          return s.next();
      }
  
      static int gcd(int a,int b)
      {
          if(b==0)
          {
              return a;
          }
          return gcd(b,a%b);
      }
      static long gcd(long a,long b)
      {
          if(b==0)
          {
              return a;
          }
          return gcd(b,a%b);
      }
      static int MOD= (int) (1e9+7);
  
      public static void primeFactors(int n)
      {
          // Print the number of 2s that divide n
          while (n % 2 == 0) {
              System.out.print(2 + " ");
              n /= 2;
          }
  
          // n must be odd at this point.  So we can
          // skip one element (Note i = i +2)
          for (int i = 3; i <= Math.sqrt(n); i += 2) {
              // While i divides n, print i and divide n
              while (n % i == 0) {
                  System.out.print(i + " ");
                  n /= i;
              }
          }
  
          // This condition is to handle the case whien
          // n is a prime number greater than 2
          if (n > 2)
              System.out.print(n);
          System.out.println();
      }
  
      static class Node
      {
          int i,j;
  
          public Node(int i, int j) {
              this.i = i;
              this.j = j;
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || getClass() != o.getClass()) return false;
              Node node = (Node) o;
              return i == node.i && j == node.j;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(i, j);
          }
      }
  
      public static void main(String[] args){
          StringBuilder ans = new StringBuilder();
          int t = ri();
  //        int t=1;
          while (t-- > 0)
          {
              int n=ri();
              long[] arr=ral(n);
              long res = 0;
              for(int i=1;i<n;i++)
              {
                  long prod = arr[i]*arr[i-1];
                  res = Math.max(prod,res);
              }
              ans.append(res).append("\n");
  
          }
          out.print(ans);
          out.flush();
  
      }
  }
  
  
  