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 Main
  {
  	public static void main(String[] args) {
  		Scanner sc=new Scanner(System.in);
  		int t=sc.nextInt();
  		for(int j=0;j<t;j++){
  		    String s=sc.next();
  		    int l=s.length();
  		    int c=0;
  		    if(l%2==0){
  		        char m[]=new char[l/2];
  		        char n[]=new char[l/2];
  		        for(int i=0;i<l/2;i++){
  		            m[i]=s.charAt(i);
  		        }
  		        int k=0;
  		        for(int i=l/2;i<l;i++){
  		            n[k]=s.charAt(i);
  		            k++;
  		        }
  		        for(int i=0;i<l/2;i++){
  		            if(m[i]==n[i]) c++;
  		            else{
  		                c=0;
  		                break;
  		            }
  		        }
  		    }
  		    if(c==l/2 && l!=1)System.out.println("YES");
  		    else if(c==0) System.out.println("NO");
  		}
  	}
  }