import sys

sys.setrecursionlimit(10 ** 6)
from collections import *
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]

def main():
    w, h = MI()
    mm = LLI(h)
    fin = set()
    bfs = deque()
    # [距離,行,列,前のマスの値]
    bfs.append([0, 0, 0, -1])
    bfs.append([0, 0, 0, 10])
    fin=set()
    while bfs:
        d, i, j, pm = bfs.popleft()
        if (i, j, pm) in fin:continue
        fin.add((i, j, pm))
        m = mm[i][j]
        for di, dj in dij:
            ni, nj = i + di, j + dj
            if ni < 0 or nj < 0 or ni >= h or nj >= w: continue
            nm = mm[ni][nj]
            if nm == m or nm==pm or pm<m<nm or pm>m>nm: continue
            if (ni,nj,m) in fin:continue
            if (ni, nj) == (h - 1, w - 1):
                print(d + 1)
                exit()
            bfs.append([d + 1, ni, nj, m])
    print(-1)

main()