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.io.*;
  import java.util.*;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.atomic.AtomicLong;
  import java.util.logging.Logger;
  import java.util.stream.Collectors;
  
  public class Trial {
  
      static char[][]grid;
      static boolean[][]visited;
      public static boolean dfs(int r, int c, int n) {
          if (r >= 2 || r < 0 || c < 0 || c>=n || grid[r][c] == '1' || visited[r][c]) {
              return false;
          }
          if (r == 1 && c == n -1) {
              return true;
          }
          visited[r][c] = true;
          return dfs(r + 1, c + 1, n) || dfs(r - 1, c + 1, n) ||
          dfs(r + 1, c, n) || dfs(r, c + 1, n) || dfs(r - 1, c, n) ;
      }
      public static void main(String[] args) throws IOException {
  
          Scanner sc = new Scanner(System.in);
          PrintWriter pw = new PrintWriter(System.out);
  
          int q = sc.nextInt();
          while (q-- > 0) {
              int n = sc.nextInt();
              grid = new char[2][n];
              visited = new boolean[2][n];
              for (int j = 0; j < 2; j++) {
                  String s = sc.next();
                  for (int i = 0; i < n; i++) {
                      grid[j][i] = s.charAt(i);
                  }
              }
              pw.println(dfs(0,0,n)? "YES": "NO");
          }
          pw.flush();
          pw.close();
      }
  
      // inclusive
      private static void rotate(int[] arr, int l, int r) {
          int temp = arr[r];
          for (int i = r - 1; i >= l; i--) {
              arr[i + 1] = arr[i];
          }
          arr[l] = temp;
      }
  
      static class Scanner {
          StringTokenizer st;
          BufferedReader br;
  
          public Scanner(InputStream System) throws FileNotFoundException {
              br = new BufferedReader(new InputStreamReader(System));
          }
  
          public String next() throws IOException {
              while (st == null || !st.hasMoreTokens())
                  st = new StringTokenizer(br.readLine());
              return st.nextToken();
          }
  
          public String nextLine() throws IOException {
              return br.readLine();
          }
  
          public int nextInt() throws IOException {
              return Integer.parseInt(next());
          }
  
          public double nextDouble() throws IOException {
              return Double.parseDouble(next());
          }
  
          public char nextChar() throws IOException {
              return next().charAt(0);
          }
  
          public Long nextLong() throws IOException {
              return Long.parseLong(next());
          }
  
          public boolean ready() throws IOException {
              return br.ready();
          }
  
          public void waitForInput() {
              for (long i = 0; i < 3e9; i++)
                  ;
          }
      }
  
      static class Pair {
          int a;
          int b;
          boolean asc;
  
          Pair(int a, int b, boolean asc) {
              this.a = a;
              this.b = b;
              this.asc = asc;
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || getClass() != o.getClass()) return false;
              Pair pair = (Pair) o;
              return a == pair.a &&
                      b == pair.b &&
                      asc == pair.asc;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(a, b, asc);
          }
      }
  }
  