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 s1 {
  	public static void main(String[] args) throws Exception {
  		FastScanner scan=new FastScanner(System.in);
  		PrintWriter out=new PrintWriter(System.out);
  
  //		int T=1;
  		int T=scan.nextInt();
  		while(T-->0) {
  
  			int n=scan.nextInt();
  			int[] a=new int[n];
  			long best=Integer.MIN_VALUE;
  			for(int i=0;i<n;i++) {
  				a[i]=scan.nextInt();
  			}
  
  			for(int i=1;i<n;i++) {
  				best=Math.max(best,(long)a[i]*a[i-1]);
  			}
  
  
  			out.println(best);
  
  		} out.close();
  	}
  }
  
  class Pair {
  	Integer a,b;
  	Pair(int a,int b) {
  		this.a=a;
  		this.b=b;
  	}
  }
  
  class FastScanner {
  	private InputStream stream;
  	private byte[] buf=new byte[1024];
  	private int curChar;
  	private int numChars;
  
  	public FastScanner(InputStream stream) { this.stream=stream; }
  
  	int read() {
  		if(numChars==-1) throw new InputMismatchException();
  		if(curChar>=numChars) {
  			curChar=0;
  			try { numChars=stream.read(buf); }
  			catch(IOException e) { throw new InputMismatchException(); }
  			if(numChars<=0) return -1;
  		} return buf[curChar++];
  	}
  
  	boolean isSpaceChar(int c) { return c==' '||c=='\n'||c=='\r'||c=='\t'||c==-1; }
  
  	boolean isEndline(int c) { return c=='\n'||c=='\r'||c==-1; }
  
  	int nextInt() { return Integer.parseInt(next()); }
  
  	long nextLong() { return Long.parseLong(next()); }
  
  	double nextDouble() { return Double.parseDouble(next()); }
  
  	String next() {
  		int c=read();
  		while(isSpaceChar(c)) c=read();
  		StringBuilder res=new StringBuilder();
  		do {
  			res.appendCodePoint(c);
  			c=read();
  		} while(!isSpaceChar(c));
  		return res.toString();
  	}
  
  	String nextLine() {
  		int c=read();
  		while(isEndline(c)) c=read();
  		StringBuilder res=new StringBuilder();
  		do {
  			res.appendCodePoint(c);
  			c=read();
  		} while(!isEndline(c));
  		return res.toString();
  	}
  }