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 CodeForce {
  
  	public static void main(String[] args) {
  		// TODO Auto-generated method stub
  		Scanner kbd=new Scanner(System.in);
  		int t=kbd.nextInt();
  		
  		while(t-->0)
  		{
  			String input=kbd.next();
  			int size=input.length();
  			if(size%2!=0) System.out.println("NO");
  			else
  			{
  				int mid=size/2;
  				String a=input.substring(0,mid);
  				String b=input.substring(mid);
  				
  				if(a.equals(b)) 
  					System.out.println("YES");
  				else System.out.println("NO");
  			}
  				
  		}
  	}
  
  }
  