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.util.* ;
  
  
   
  public class App {
      public static void main (String[] args) throws java.lang.Exception {
  		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
          //reader = new BufferedReader(new FileReader(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\input.txt")));
  		BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
          //writer = new BufferedWriter(new FileWriter(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\output.txt")));
  		//int tests = Integer.parseInt(reader.readLine());
          int tests = 1;
  		//StringBuilder sb = new StringBuilder(tests);
  		while (tests-- > 0){
  		    solve(reader, writer);
              writer.write("\n");
  		}
  		reader.close();
          writer.flush();
          writer.close();
      }
  
   
      static void solve(BufferedReader reader, BufferedWriter writer) throws  IOException {
  		int tests = Integer.parseInt(reader.readLine());
  		for (int i = 0; i < tests; i++) {
  			int n = Integer.parseInt(reader.readLine());
  			int[] a = new int[n];
  			long product = 0;
  			String[] input = reader.readLine().split(" ");
  			for(int j = 0; j < n; j++) {
  				a[j] = Integer.parseInt(input[j]);
  			}
  			for(int j = 1; j < n; j++) {
  				product = Math.max(product, (long)a[j] * a[j - 1]);
  			}
  			writer.write(product + "\n");
  		}
  	}
  }
  