from itertools import product
from math import inf, isinf
DIJ = ((0, 1), (1, 0), (0, -1), (-1, 0))


def main():
    H, W = map(int, input().split())

    def is_in_board(position: tuple[int, int]) -> bool:
        return 0 <= position[0] < H and 0 <= position[1] < W
    board = [list(map(int, input().split())) for _ in range(H)]

    coords = sorted([(board[h][w], h, w)
                    for h, w in product(range(H), range(W))])
    distances = [[-inf] * W for _ in range(H)]
    for coord in coords:
        if isinf(distances[coord[1]][coord[2]]):
            distances[coord[1]][coord[2]] = 1

        for dij in DIJ:
            neighbor = (coord[1] + dij[0], coord[2] + dij[1])
            if not is_in_board(neighbor):
                continue
            if board[coord[1]][coord[2]] >= board[neighbor[0]][neighbor[1]]:
                continue
            if distances[neighbor[0]][neighbor[1]
                                      ] < distances[coord[1]][coord[2]] + 1:
                distances[neighbor[0]][neighbor[1]
                                       ] = distances[coord[1]][coord[2]] + 1

    print(max(max(row) for row in distances))


if __name__ == "__main__":
    main()