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 sqst{
  
  	public static void main(String args[]){
  		Scanner sc = new Scanner(System.in);
  		
  		int t = sc.nextInt();
  		sc.nextLine();
  
  		for(int i=0; i<t; i++){
  			String s = sc.nextLine();
  			int n = s.length();
  
  			//System.out.println(n);
  
  			if(n%2 != 0 || n == 0){
  				System.out.println("NO");
  				continue;
  			}
  
  
  			int m = (n+1)/2;
  
  			boolean st = false;
  
  			for(int j=0; j<m; j++){
  				if(s.charAt(j) != s.charAt(j+m)){
  					st = true;
  					break;
  				}	
  			}
  
  			if(st == true)
  				System.out.println("NO");
  			else
  				System.out.println("YES");
  
  		}
  		return;
  	}
  }