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.*;
   
   
  public class test {
   
      public static void main(String[] args)  {
           Scanner sc = new Scanner(System.in);
  		int t = sc.nextInt();
  		while(t!=0){
  		    boolean f = false;
  		    String s = sc.next();
  		    if(s.length()%2!=0){
  		        System.out.println("NO");
  		    }else{
  		    int n = s.length()/2;
  		    int i = 0;
  		    while(n<s.length()){
  		        if(s.charAt(i)!=s.charAt(n)){
  		            System.out.println("NO");
  		            f=true;
  		            break;
  		        }
  		        n++;
  		        i++;
  		    }
  		    if(!f){
  		    System.out.println("YES");
  		    }
  		    }
  		    t--;
  		}
          
      }
  }