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 String_square {
  	static Scanner sc = new Scanner(System.in);
  	public static void main(String[] args)
  	{
  		int size = sc.nextInt();
  		for(int k=0; k<size; k++)
  		{
  				
  			
  			String s= sc.next();
  			int n = s.length();
  			
  			if(n%2!=0)
  			{
  				System.out.println("no");
  				continue;
  			}
  			int half = n/2;
  			int i=0;
  			for(i=0; i<half; i++)
  			{
  				if(s.charAt(i)==s.charAt(i+half))continue;
  				else
  				{
  					System.out.println("no");
  					break;
  					
  				}
  			}
  			if(i==half)
  			{
  				System.out.println("Yes");
  			}
  		}
  			
  	}
  }
  