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 HelloWorld {
  
  	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 st= sc.nextLine();
  		    int n= st.length();
  		    if(n%2!=0) {
  		    	System.out.println("NO");
  		    }
  		    else {
  		    	boolean is_squre=false;
  		    	for(int j=0;j<(n/2);j++) {
  		    		if(st.charAt(j)==st.charAt(n/2 + j))
  		    		{
  		    			is_squre=true;
  		    		}else {
  		    			is_squre=false;
  		    			
  		    		  break;
  		    		}
  		    	}
  		    	if(is_squre) {
  		    		System.out.println("YES");
  		    	}
  		    	else {
  		    		System.out.println("NO");
  		    	}
  		    }
  		    
  			
  		}
  		
  
  	}
  
  }
  