from heapq import heappop, heappush
from itertools import count

DIJ = ((0, 1), (1, 0), (0, -1), (-1, 0))


def main():
    H, W = map(int, input().split())
    board = [list(map(int, input().split())) for _ in range(H)]

    color_0 = set(((H - 1, W - 1),))
    color_1 = set(((0, 0),))

    color_0_neighbors = []
    color_1_neighbors = []
    heappush(color_0_neighbors, (board[H - 2][W - 1], H - 2, W - 1))
    heappush(color_0_neighbors, (board[H - 1][W - 2], H - 1, W - 2))
    heappush(color_1_neighbors, (board[1][0], 1, 0))
    heappush(color_1_neighbors, (board[0][1], 0, 1))

    for idx in count(1):

        if idx % 2 == 1:
            h, w = 0, 0
            while (h, w) in color_1:
                num, h, w = heappop(color_1_neighbors)

            color_1.add((h, w))
            for dij in DIJ:
                neighbor = (h + dij[0], w + dij[1])
                if not (0 <= neighbor[0] < H) or not (0 <= neighbor[1] < W):
                    continue
                if neighbor in color_0:
                    break
                if neighbor in color_1:
                    continue
                heappush(color_1_neighbors,
                         (board[neighbor[0]][neighbor[1]],
                          neighbor[0],
                             neighbor[1]))
            else:
                continue
            break
        else:
            h, w = H - 1, W - 1
            while (h, w) in color_0:
                num, h, w = heappop(color_0_neighbors)
            color_0.add((h, w))
            for dij in DIJ:
                neighbor = (h + dij[0], w + dij[1])
                if not (0 <= neighbor[0] < H) or not (0 <= neighbor[1] < W):
                    continue
                if neighbor in color_1:
                    break
                if neighbor in color_0:
                    continue
                heappush(color_0_neighbors,
                         (board[neighbor[0]][neighbor[1]],
                          neighbor[0],
                             neighbor[1]))
            else:
                continue
            break
    print(idx)


if __name__ == "__main__":
    main()