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.*;
  
   // Author : Savan Patel
  public class A implements Runnable {
  
      static class PP{
          int univ;
          int skill;
          PP(int u,int s){
              univ=u;
              skill=s;
          }
      }
  
      public void run() {
         	
          InputReader sc = new InputReader(System.in);
          PrintWriter out = new PrintWriter(System.out);
         
          int t=sc.nextInt();
          while(t-->0){
              int n=sc.nextInt();//8 7 1 3 4 2 5 
              
              long a[]=new long[n];
              for(int i=0;i<n;i++){
                  a[i]=sc.nextLong();
              }
              
              long max=a[0]*a[1];
  
              for(int i=1;i<n-1;i++){
                  long x=max;
                  max=Math.max(max,Math.max(1L*a[i]*a[i-1],1L*a[i]*a[i+1]));
                  
              }
              max=Math.max(max,a[n-1]*1L*a[n-2]);
              out.println(max);
  
          }
  
          out.close();
  
      }
   
  
  //========================================================================
  
  	
  	static void scanArray(int a[],InputReader sc)
  	{
  		for(int i=0;i<a.length;i++)
  		{
  			a[i]=sc.nextInt();
  		}
          //Arrays.sort(a);
  	}
  
  	static class pair<U extends Comparable<U>, V extends Comparable<V>> implements Comparable<pair<U, V>> {
          public U x;
          public V y;
  
          public pair(U x, V y) {
              this.x = x;
              this.y = y;
          }
  
          public int compareTo(pair<U, V> other) {
              int i = x.compareTo(other.x);
              if (i != 0) return i;
              return y.compareTo(other.y);
          }
  
          public String toString() {
              return x.toString() + " " + y.toString();
          }
  
          public boolean equals(Object obj) {
              if (this.getClass() != obj.getClass()) return false;
              pair<U, V> other = (pair<U, V>) obj;
              return x.equals(other.x) && y.equals(other.y);
          }
  
          public int hashCode() {
              return 31 * x.hashCode() + y.hashCode();
          }
  
      }
  
  
      static class InputReader {
          private InputStream stream;
          private byte[] buf = new byte[1024];
          private int curChar;
          private int numChars;
          private SpaceCharFilter filter;
          private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   
          public InputReader(InputStream stream) {
              this.stream = stream;
          }
         
          public 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++];
          }
       
          public String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              }
              catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
          public int nextInt() {
              int c = read();
             
              while(isSpaceChar(c))
                  c = read();
             
              int sgn = 1;
             
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
             
              int res = 0;
              do {
                  if(c<'0'||c>'9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              }
              while (!isSpaceChar(c));
             
              return res * sgn;
          }
         
          public long nextLong() {
              int c = read();
              while (isSpaceChar(c))
                  c = read();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
              long res = 0;
             
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              }
              while (!isSpaceChar(c));
                  return res * sgn;
          }
         
          public double nextDouble() {
              int c = read();
              while (isSpaceChar(c))
                  c = read();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
              double res = 0;
              while (!isSpaceChar(c) && c != '.') {
                  if (c == 'e' || c == 'E')
                      return res * Math.pow(10, nextInt());
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              }
              if (c == '.') {
                  c = read();
                  double m = 1;
                  while (!isSpaceChar(c)) {
                      if (c == 'e' || c == 'E')
                          return res * Math.pow(10, nextInt());
                      if (c < '0' || c > '9')
                          throw new InputMismatchException();
                      m /= 10;
                      res += (c - '0') * m;
                      c = read();
                  }
              }
              return res * sgn;
          }
         
          public String readString() {
              int c = read();
              while (isSpaceChar(c))
                  c = read();
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = read();
              }
              while (!isSpaceChar(c));
             
              return res.toString();
          }
       
          public boolean isSpaceChar(int c) {
              if (filter != null)
                  return filter.isSpaceChar(c);
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
       
          public String next() {
              return readString();
          }
         
          public interface SpaceCharFilter {
              public boolean isSpaceChar(int ch);
          }
      }
  
      public static void main(String args[]) throws Exception {
          new Thread(null, new A(),"Main",1<<27).start();
      }
  }
  