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.lang.reflect.Array;
  import java.util.*;
  
  public class Main {
      public static void main(String[] args) throws IOException {
          OutputStream outputStream = System.out;
          PrintWriter out = new PrintWriter(outputStream);
          FastReader in = new FastReader();
          test a=new test();
          a.solve(in,out);
          out.close();
      }
  }
  class test{
      public void solve(FastReader in, PrintWriter out) {
  
         int t = in.nextInt();
         while(t-->0){
             int n= in.nextInt();
  
             long[] a = new long[n];
             long max = Long.MIN_VALUE;
             long ans=Long.MIN_VALUE;
             a[0] = in.nextLong();
             for(int i=1;i<n;i++){
                 a[i] = in.nextLong();
                 ans = Math.max(ans,a[i]*a[i-1]);
             }
             out.println(ans);
         }
      }
  
      void printarr(long[] a){
          for(long i: a){
              System.out.print(i+" ");
          }
          System.out.println();
      }
  
      public boolean isPrime(long n){
          if(n==1 || n%2==0){
              return false;
          }
          for(long i=3;i*i<=n;i+=2){
              if(n%i==0)
                  return false;
          }
          return true;
      }
      List<Integer> sieve(int n){
          int[] b = new int[n+1];
          Arrays.fill(b,0);
          b[0] = b[1] = 1;
          for(int i=2;i<=n;i++){
              if(b[i]==0){
                  for(int j =2*i;j<=n;j+=i){
                      b[j] = 1;
                  }
              }
          }
          List<Integer> l = new ArrayList<>();
          for(int i=0;i<b.length;i++){
              if(b[i]==0){
                  l.add(i);
              }
          }
          return l;
      }
      List<Integer> segmentedSieve(long l , long r, List<Integer> prime){
          if(l==1)
              l++;
          int size = (int)(r-l+1);
          boolean[] b = new boolean[size];
          Arrays.fill(b,true);
          for(int i : prime){
              if(i*i<=r){
                  int lim = (int)(l/i)*i;
                  if(lim<l)
                      lim+=i;
                  for(;lim<=r;lim+=i){
                      if (lim!=i)
                          b[(int)(lim-l)] = false;
                  }
              }
          }
          List<Integer> list = new ArrayList<>();
          for (int i=0;i<b.length;i++){
              if(b[i]){
                  list.add((int)(i+l));
              }
          }
          return list;
      }
  
      long gcd(long a, long b){
          if(b==0){
              return a;
          }
          return gcd(b,a%b);
      }
  
      public int BinarySearch(int[] a,int low,int high, int key){
          if(low>high){
              return -1;
          }
          int mid = low +(high-low)/2;
          if(key==a[mid]){
              return mid;
          }
          else if(key>a[mid]){
              return BinarySearch(a,mid+1,high,key);
          }
          else{
              return BinarySearch(a,low,mid-1,key);
          }
      }
  }
  
  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;
      }
  }
  