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.util.function.Function;
  import java.util.stream.Collectors;
  import java.io.*;
  import java.math.*;
  import java.text.*;
  
  public class Main {
  
      static InputReader in = new InputReader(System.in);
      static OutputWriter out = new OutputWriter(System.out);
  
  
  
  
  
  
  
  
      public static void main(String[] args)
              throws NumberFormatException, IOException {
          // TODO Auto-generated method stub
          BufferedReader br = new BufferedReader(
                  new InputStreamReader(System.in));
          int t = i();
          PrintWriter out = new PrintWriter(System.out);
          while (t > 0) {
  
              int n=i();
              int arr[]=new int[n];
              for(int i=0;i<n;i++) {
                  arr[i]=i();
              }
  
              long ans=0L;
              for(int i=0;i<n-1;i++) {
                  ans=Math.max(ans, arr[i]*(long)arr[i+1]);
              }
              System.out.println(ans);
  
  
  
  
  
  
  
              t--;
  
          }
          out.close();
  
          //      long l=l();
          //      String s=s();     //    ONLY BEFORE SPACE IN STRING , ELSE USE BUFFER-READER
  
      }
  
      public static long pow(long a, long b) {
          long m = 1000000007;
          long result = 1;
          while (b > 0) {
              if (b % 2 != 0) {
                  result = (result * a) % m;
                  b--;
              }
              a = (a * a) % m;
              b /= 2;
          }
          return result % m;
      }
  
      public static long gcd(long a, long b) {
          if (a == 0) {
              return b;
          }
          return gcd(b % a, a);
      }
  
      public static long lcm(long a, long b) {
          return a * (b / gcd(a, b));
      }
  
      public static long l() {
          String s = in.String();
          return Long.parseLong(s);
      }
  
      public static void pln(String value) {
          System.out.println(value);
      }
  
      public static int i() {
          return in.Int();
      }
  
      public static String s() {
          return in.String();
      }
  
  }
  
  class pair {
      int x, y;
  
      pair(int x, int y) {
          this.x = x;
          this.y = y;
      }
  }
  
  class CompareValue {
  
      static void compare(pair arr[], int n) {
          Arrays.sort(arr, new Comparator<pair>() {
              public int compare(pair p1, pair p2) {
                  return p1.y - p2.y;
              }
          });
      }
  }
  
  class CompareKey {
      static void compare(pair arr[], int n) {
          Arrays.sort(arr, new Comparator<pair>() {
              public int compare(pair p1, pair p2) {
                  return p2.x - p1.x;
              }
          });
      }
  }
  
  class InputReader {
      private InputStream stream;
      private byte[] buf = new byte[1024];
      private int curChar;
      private int numChars;
      private SpaceCharFilter filter;
  
      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 int Int() {
          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 String String() {
          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 String();
      }
  
      public interface SpaceCharFilter {
          public boolean isSpaceChar(int ch);
      }
  
      public double readDouble() {
          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, Int());
              }
              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, Int());
                  }
                  if (c < '0' || c > '9') {
                      throw new InputMismatchException();
                  }
                  m /= 10;
                  res += (c - '0') * m;
                  c = read();
              }
          }
          return res * sgn;
      }
  }
  
  class OutputWriter {
      private final PrintWriter writer;
  
      public OutputWriter(OutputStream outputStream) {
          writer = new PrintWriter(
                  new BufferedWriter(new OutputStreamWriter(outputStream)));
      }
  
      public OutputWriter(Writer writer) {
          this.writer = new PrintWriter(writer);
      }
  
      public void print(Object... objects) {
          for (int i = 0; i < objects.length; i++) {
              if (i != 0) {
                  writer.print(' ');
              }
              writer.print(objects[i]);
          }
          writer.flush();
      }
  
      public void printLine(Object... objects) {
          print(objects);
          writer.println();
          writer.flush();
      }
  
      public void close() {
          writer.close();
      }
  
      public void flush() {
          writer.flush();
      }
  }
  
  class IOUtils {
      public static int[] readIntArray(InputReader in, int size) {
          int[] array = new int[size];
          for (int i = 0; i < size; i++)
              array[i] = in.Int();
          return array;
      }
  }
  
  