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.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.*;
   
  public class cf2{
      public 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;
          }
      
        }
          
      public static void main(String[] args) {
          FastReader fr = new FastReader();
          int t = fr.nextInt();
          while(t-->0){
              int n = fr.nextInt();
            long [] arr =  new long[n];
            for(int i=0;i<n;i++){
                arr[i] = fr.nextInt();
            }
            
            long ans = 0;
            for(int i=0;i<(n-1);i++){
              long n1 =arr[i];
              long n2  = arr[i+1];
              if((n1*n2)> ans){
                  ans=(n1*n2);
              }
            }
            
              System.out.println(ans);  
          }
          return;
          
      }
  }
  // 381274500335
  // 1784478530