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.*;
  import java.text.DecimalFormat;
  
  public class A {
      static long mod=(long)1e9+7;
      static long mod1=998244353;
      static InputStream inputStream = System.in;
      static OutputStream outputStream = System.out;
      static InputReader in = new InputReader(inputStream);
      static PrintWriter out = new PrintWriter(outputStream);
  
      public static void main(String[] args) throws IOException {
  
          int t= in.nextInt();
          while(t-->0) {
  
              int n = in.nextInt();
              int[] arr = in.readArray(n);
  
              long max = 0;
              for(int i = 0;i<n-1;i++){
                  long prod = (long) arr[i] *arr[i+1];
                  max = Math.max(max,prod);
              }
  
              out.println(max);
  
  
          }
          out.close();
      }
  
  
  
  
      static final Random random=new Random();
  
      static void ruffleSort(int[] a) {
          int n=a.length;//shuffle, then sort
          for (int i=0; i<n; i++) {
              int oi=random.nextInt(n), temp=a[oi];
              a[oi]=a[i]; a[i]=temp;
          }
          Arrays.sort(a);
      }
      static long gcd(long x, long y){
          if(x==0)
              return y;
          if(y==0)
              return x;
          long r=0, a, b;
          a = Math.max(x, y);
          b = Math.min(x, y);
          r = b;
          while(a % b != 0){
              r = a % b;
              a = b;
              b = r;
          }
          return r;
      }
      static long modulo(long a,long b,long c){
          long x=1,y=a%c;
          while(b > 0){
              if(b%2 == 1)
                  x=(x*y)%c;
              y = (y*y)%c;
              b = b>>1;
          }
          return  x%c;
      }
      public static void debug(Object... o){
          System.err.println(Arrays.deepToString(o));
      }
  
      static int upper_bound(int[] arr,int n,int x){
          int mid;
          int low=0;
          int high=n;
          while(low<high){
              mid=low+(high-low)/2;
              if(x>=arr[mid])
                  low=mid+1;
              else
                  high=mid;
          }
          return low;
      }
  
      static int lower_bound(int[] arr,int n,int x){
          int mid;
          int low=0;
          int high=n;
          while(low<high){
              mid=low+(high-low)/2;
              if(x<=arr[mid])
                  high=mid;
              else
                  low=mid+1;
          }
          return low;
      }
      static String printPrecision(double d){
          DecimalFormat ft = new DecimalFormat("0.00000000000");
          return String.valueOf(ft.format(d));
      }
      static int countBit(long mask){
          int ans=0;
          while(mask!=0){
              mask&=(mask-1);
              ans++;
          }
          return ans;
      }
  
      static class InputReader {
          public BufferedReader reader;
          public StringTokenizer tokenizer;
  
          public InputReader(InputStream stream) {
              reader = new BufferedReader(new InputStreamReader(stream), 32768);
              tokenizer = null;
          }
  
          public String next() {
              while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                  try {
                      tokenizer = new StringTokenizer(reader.readLine());
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
              }
              return tokenizer.nextToken();
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
  
          public double nextDouble() {
              return Double.parseDouble(next());
          }
  
          public int[] readArray(int n) {
              int[] arr = new int[n];
              for (int i = 0; i < n; i++) arr[i] = nextInt();
              return arr;
          }
      }
  }