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.Arrays;
  import java.util.Scanner;
  
  public class A {
  
  	public static void main(String[] args) {
  		// TODO Auto-generated method stub
  		Scanner sc=new Scanner(System.in);
  		int t=sc.nextInt();
  		
  		while(t-->0) {
  				String str=sc.next();
  				if(str.length()%2!=0){
  					System.out.println("NO");
  				}
  				else {
  					int n=str.length()/2;
  					String str1=str.substring(0,n);
  					String str2=str.substring(n,str.length());
  					if(str1.equals(str2)) {
  						System.out.println("YES");
  					}
  					else {
  						System.out.println("NO");
  					}
  				}
  	}
  
  }
  }
  