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.util.*;
  import java.io.*;
  public class Broken_Keyboard  {
  	static Scanner sc=new Scanner(System.in);
  	static PrintWriter pw=new PrintWriter(System.out);
  	
  	public static void main(String[] args) throws IOException, InterruptedException {
  	StringBuilder sb ;
  	int t=sc.nextInt();String s;
  	while(t-->0) {
  		int n=sc.nextInt();
  		long max=Integer.MIN_VALUE;long min=Integer.MAX_VALUE;
  		long []a=new long [n];int c1=0,c2=0;long max2=0,temp=0;
  		for(int i=0;i<n;i++) {
  			a[i]=sc.nextLong();
  			if(i>0) {
  				temp=a[i]*a[i-1];
  				if(temp>max2)
  					max2=temp;
  			}
  			if(a[i]>max) {
  				max=a[i];c1=i;
  			}
  			if(a[i]<min) {
  				min=a[i];c2=i;
  			}
  		}
  		long sum1=max*min,sum2=0,sum3=0;
  		if(c1==n-1) 
  			sum3=max*a[c1-1];
  		else if(c1==0)
  			sum2=max*a[c1+1];
  		else {
  			sum2=max*a[c1+1];
  			sum3=max*a[c1-1];
  		}
  		pw.println(Math.max(Math.max(sum1, max2), Math.max(sum2, sum3)));
  	}
      
  	
      pw.flush();
  	}
  	static class Scanner {
  		StringTokenizer st;
  		BufferedReader br;
   
  		public Scanner(InputStream s) {
  			br = new BufferedReader(new InputStreamReader(s));
  		}
   
  		public Scanner(FileReader r) {
  			br = new BufferedReader(r);
  		}
   
  		public String next() throws IOException {
  			while (st == null || !st.hasMoreTokens())
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  		public String readAllLines(BufferedReader reader) throws IOException {
  		    StringBuilder content = new StringBuilder();
  		    String line;
  		    
  		    while ((line = reader.readLine()) != null) {
  		        content.append(line);
  		        content.append(System.lineSeparator());
  		    }
  
  		    return content.toString();
  		}
  		public int nextInt() throws IOException {
  			return Integer.parseInt(next());
  		}
   
  		public long nextLong() throws IOException {
  			return Long.parseLong(next());
  		}
   
  		public String nextLine() throws IOException {
  			return br.readLine();
  		}
   
  		public double nextDouble() throws IOException {
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if (x.charAt(0) == '-') {
  				neg = true;
  				start++;
  			}
  			for (int i = start; i < x.length(); i++)
  				if (x.charAt(i) == '.') {
  					res = Long.parseLong(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				} else {
  					sb.append(x.charAt(i));
  					if (dec)
  						f *= 10;
  				}
  			res += Long.parseLong(sb.toString()) / f;
  			return res * (neg ? -1 : 1);
  		}
   
  		public long[] nextlongArray(int n) throws IOException {
  			long[] a = new long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
   
  		public Long[] nextLongArray(int n) throws IOException {
  			Long[] a = new Long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
   
  		public int[] nextIntArray(int n) throws IOException {
  			int[] a = new int[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
   
  		public Integer[] nextIntegerArray(int n) throws IOException {
  			Integer[] a = new Integer[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
   
  		public boolean ready() throws IOException {
  			return br.ready();
  		}
   
  	}
   
  }
  
  	
  
  	
  	
  