description: Monocarp is playing a computer game. Now he wants to complete the first level of this game.
  
  A level is a rectangular grid of 2 rows and n columns. Monocarp controls a character, which starts in cell (1, 1) — at the intersection of the 1-st row and the 1-st column.
  
  Monocarp's character can move from one cell to another in one step if the cells are adjacent by side and/or corner. Formally, it is possible to move from cell (x_1, y_1) to cell (x_2, y_2) in one step if |x_1 - x_2| ≤ 1 and |y_1 - y_2| ≤ 1. Obviously, it is prohibited to go outside the grid.
  
  There are traps in some cells. If Monocarp's character finds himself in such a cell, he dies, and the game ends.
  
  To complete a level, Monocarp's character should reach cell (2, n) — at the intersection of row 2 and column n.
  
  Help Monocarp determine if it is possible to complete the level.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases. Then the test cases follow. Each test case consists of three lines.
  
  The first line contains a single integer n (3 ≤ n ≤ 100) — the number of columns.
  
  The next two lines describe the level. The i-th of these lines describes the i-th line of the level — the line consists of the characters '0' and '1'. The character '0' corresponds to a safe cell, the character '1' corresponds to a trap cell.
  
  Additional constraint on the input: cells (1, 1) and (2, n) are safe.
  
  Output
  
  For each test case, output YES if it is possible to complete the level, and NO otherwise.
  
  Example
  
  Input
  
  
  4
  3
  000
  000
  4
  0011
  1100
  4
  0111
  1110
  6
  010101
  101010
  
  
  Output
  
  
  YES
  YES
  NO
  YES
  
  Note
  
  Consider the example from the statement.
  
  In the first test case, one of the possible paths is (1, 1) → (2, 2) → (2, 3).
  
  In the second test case, one of the possible paths is (1, 1) → (1, 2) → (2, 3) → (2, 4).
  
  In the fourth test case, one of the possible paths is (1, 1) → (2, 2) → (1, 3) → (2, 4) → (1, 5) → (2, 6).
solution: import java.util.Scanner;
   
  public class Main {
   
  		static boolean check=false;
  		static void game(int i , int j, int n , String[] grid) {
  
  		if(i==1 && j==n-1) 
  			check=true;
  		else if(j< n-1 && grid[i].charAt(j+1)=='0') 
  			game(i,j+1,n,grid);
  		else if(i<1 && grid[i+1].charAt(j)=='0' ) 
  			game(i+1,j,n,grid);
  		else if( i<1 && j<n-1 && grid[i+1].charAt(j+1)=='0') 
  			game(i+1,j+1,n,grid);
  		else if( i>0 && j<n-1 && grid[i-1].charAt(j+1)=='0') 
  			game(i-1,j+1,n,grid);
  		else 
  			return;
   
  		
  	}
  	
  	public static void main(String[] args) {
  		String [] grid= new String[2];
  		int testCases;
  		Scanner scanner= new Scanner(System.in);
  		testCases= scanner.nextInt();
  		int n;
  		
  		for (int i=0 ; i<testCases ; i++) {
  			boolean result;
  			n=scanner.nextInt();
  			scanner.nextLine();
  			grid[0]= scanner.nextLine();
  			grid[1]=scanner.nextLine();
  			game(0,0,n,grid);		
  			if(check)
  				System.out.println("YES");
  			else
  				System.out.println("NO");
  			check=false;
  			
  			
  		}
  		
  	}
   
  }