description: A string is called square if it is some string written twice in a row. For example, the strings "aa", "abcabc", "abab" and "baabaa" are square. But the strings "aaa", "abaaab" and "abcdabc" are not square.
  
  For a given string s determine if it is square.
  
  Input
  
  The first line of input data contains an integer t (1 ≤ t ≤ 100) —the number of test cases.
  
  This is followed by t lines, each containing a description of one test case. The given strings consist only of lowercase Latin letters and have lengths between 1 and 100 inclusive.
  
  Output
  
  For each test case, output on a separate line:
  
    * YES if the string in the corresponding test case is square, 
    * NO otherwise. 
  
  
  
  You can output YES and NO in any case (for example, strings yEs, yes, Yes and YES will be recognized as a positive response).
  
  Example
  
  Input
  
  
  10
  a
  aa
  aaa
  aaaa
  abab
  abcabc
  abacaba
  xxyy
  xyyx
  xyxy
  
  
  Output
  
  
  NO
  YES
  NO
  YES
  YES
  YES
  NO
  NO
  NO
  YES
solution: import java.util.*;
  import java.lang.*;
  import java.io.*;
  public class Main
  {
  	public static void main (String[] args) throws java.lang.Exception
  	{
  		Scanner sc = new Scanner(System.in);
  		int t = sc.nextInt();
  		while(t>0)
  		{
  		    String s = sc.next();
  		    int n = s.length();
  		    if(n%2!=0)
  		    System.out.println("NO");
  		  else{
  		      int p = n/2;
  		      String ans = "YES";
  		      for(int i=0;i<p;i++)
  		      {
  		          if(s.charAt(i)!=s.charAt(p+i))
  		          {
  		              ans = "NO";
  		              break;
  		          }
  		      }
  		      System.out.println(ans);
  		  }
  		 t--;   
  		}
  	}
  }
  