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.Arrays;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.StringTokenizer;
  
  
  public  class Practice  {
  	
  	
  	
  	        public static void main(String[] args) {
  		         FastReader sc=new FastReader();
  		         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();
  		        	}
  		        	long max=Integer.MIN_VALUE;
  		        	for( int i=0;i<n-1;i++) {
  		        		max=Math.max(max, (long)arr[i]*(long)arr[i+1]);
  		        	}
  		        	System.out.println(max);
  		         }
  	        }
  	        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;
  	            }
  	        }
  	     
  	
  	}
  			
  			