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 A {
  
  	public static void main(String[] args) {
  		sc = new MyScanner();
  		out = new PrintWriter(new BufferedOutputStream(System.out));
  
  		// solution
  		int t = sc.nextInt();
  		
  		while (t != 0) {
  			
  			int n = sc.nextInt();
  			int[] arr = new int[n];
  			
  			for (int i = 0; i < n; ++i) {
  				arr[i] = sc.nextInt();
  			}
  			
  			int minIndex = 0;
  			int maxIndex = 1;
  			
  			if (arr[1] < arr[0]) {
  				minIndex = 1;
  				maxIndex = 0;
  			}
  			long res = (long)arr[minIndex] * (long)arr[maxIndex];
  			
  			/*for (int i = 2; i < n; ++i) {
  				if (arr[i] > arr[minIndex] && arr[i] < arr[maxIndex]) {
  					minIndex = i;
  				} else if (arr[i] >= arr[maxIndex]) {
  					maxIndex = i;
  				}
  				res = Math.max(res, (long)arr[minIndex] * (long)arr[maxIndex]);
  			} */
  			
  			for (int i = 2; i < n; ++i) {
  				res = Math.max(res, (long)arr[i] * (long)arr[i - 1]);
  			}
  			
  			
  			
  			
  			
  			
  			out.println(res);
  			
  			
  			
  			--t;
  		}
  		
  		out.close();
  	}
  
  	// -----------------------------------------------------------------
  
  	public static MyScanner sc;
  	public static PrintWriter out;
  
  	public static class MyScanner {
  		BufferedReader br;
  		StringTokenizer st;
  
  		public MyScanner() {
  			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;
  		}
  	}
  
  }
  