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: //package december20_2021;
  import java.util.*;
  import java.io.*;
  public class squarestring {
  
  	public static void main(String[] args)throws IOException {
  		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  		StringTokenizer st = new StringTokenizer(br.readLine());
  		int t = Integer.parseInt(st.nextToken());
  		String[] str = new String[t];
  		for(int i = 0; i < t; i++) {
  			st = new StringTokenizer(br.readLine());
  			str[i] = st.nextToken();
  		}
  		for(int i = 0; i < t; i++) {
  			
  				if(str[i].length()%2==0 && str[i].substring(0, str[i].length()/2).equals(str[i].substring(str[i].length()/2))) {
  					System.out.println("YES");
  				}
  				else {
  					System.out.println("NO");
  				}
  
  		}
  	}
  
  }
  