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.Scanner;
  
  
  public class Test{
  	public static void main(String args[]){
  		int t;
  		Scanner sc = new Scanner(System.in);
  		t = sc.nextInt();
  		while(t-- > 0){
  			String s = sc.next();
  			int strLength = s.length();
  			if(strLength % 2 == 1){
  				System.out.println("NO");
  			}else{
  				boolean flag = false;
  				int mid = strLength/2;
  				for(int i=0;i<mid;i++){
  					if(s.charAt(i) != s.charAt(mid + i)){
  						flag = true;
  						break;
  					}
  				}
  				if(flag){
  					System.out.println("NO");
  				}else{
  					System.out.println("YES");
  				}
  			}
  		}
  	}
  }