Longest Surface

import java.util.Scanner;

public class LongestSurface {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String[] input = scanner.nextLine().trim().split(" ");

        int cols = Integer.parseInt(input[0]);
        int rows = Integer.parseInt(input[1]);

        int[][] matrixOne = createMatrix(scanner, cols, rows);

        System.out.println(findMaxAdjacentCount(matrixOne));

    }

    private static int[][] createMatrix(Scanner scanner, int cols, int rows) {
        int[][] matrix = new int[cols][rows];
        for (int i = 0; i < cols; i++) {
            for (int j = 0; j < rows; j++) {
                matrix[i][j] = scanner.nextInt();
            }
        }
        return matrix;
    }

    public static int findMaxAdjacentCount(int[][] grid) {
        boolean[][] visited = createVisitGrid(grid);
        int result = 0;

        for (int row = 0; row < grid.length; row++)
            for (int col = 0; col < grid[row].length; col++)
                if (!visited[row][col])
                    result = Math.max(result, dfs(grid, visited, grid[row][col], row, col));

        return result;
    }

    private static int dfs(int[][] grid, boolean[][] visited, int expected, int row, int col) {
        if (row < 0 || row >= grid.length)
            return 0;
        if (col < 0 || col >= grid[row].length)
            return 0;
        if (visited[row][col] || grid[row][col] != expected)
            return 0;

        visited[row][col] = true;

        int depth = 1;
        depth += dfs(grid, visited, expected, row, col - 1);
        depth += dfs(grid, visited, expected, row, col + 1);
        depth += dfs(grid, visited, expected, row - 1, col);
        depth += dfs(grid, visited, expected, row + 1, col);
        return depth;
    }

    private static boolean[][] createVisitGrid(int[][] grid) {
        boolean[][] visit = new boolean[grid.length][];

        for (int row = 0; row < grid.length; row++)
            visit[row] = new boolean[grid[row].length];

        return visit;
    }
}