1012 - 반례를 모르겠습니다. JAVA

안녕하세요. 큰돌님 강의 잘 보고있습니다.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;


public class Main {
    static int[][] board;
    static boolean[][] visited;
    static int[] dy = {-1, 0, 1, 0};
    static int[] dx = {0, 1, 0, -1};
    static int yLen;
    static int xLen;
    static int cnt;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        StringBuilder sb = new StringBuilder();
        while (n-- > 0) {
            int[] given = Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
            if (given[2] == 1) {
                sb.append(1).append(System.lineSeparator());
                continue;
            }
            board = new int[given[0]][given[1]];
            visited = new boolean[given[0]][given[1]];
            yLen = given[0];
            xLen = given[1];
            for (int i = 0; i < given[2]; i++) {
                String[] numStr = br.readLine().split(" ");
                int y = Integer.parseInt(numStr[0]);
                int x = Integer.parseInt(numStr[1]);
                board[y][x] = 1;
            }
            for (int i = 0; i < yLen; i++) {
                for (int j = 0; j < xLen; j++) {
                    if (!visited[i][j] && board[i][j] == 1) {
                        dfs(i, j);
                        cnt++;
                    }
                }
            }
            sb.append(cnt).append(System.lineSeparator());
        }
        System.out.print(sb.substring(0, sb.length() - 1));
    }

    public static void dfs(int y, int x) {
        visited[y][x] = true;
        for (int i = 0; i < 4; i++) {
            int ny = y + dy[i];
            int nx = x + dx[i];
            if (ny < 0 || ny >= yLen || nx < 0 || nx >= xLen) continue;
            if (visited[ny][nx] || board[ny][nx] == 0) continue;
            dfs(ny, nx);
        }
    }
}

위 코드를 실행하면 12%, ArrayIndexOutOfBounds가 발생하는데 어떤 부분인지 알 수 있을까요?