import sys
input = sys.stdin.readline

from collections import defaultdict
from heapq import heappop,heappush,heapify

h,w=map(int,input().split())
A=[list(map(int,input().split())) for _ in range(h)]
pos=defaultdict(tuple)
for i in range(h):
    for j in range(w):
        pos[A[i][j]]=(i,j)
        
color=[[-1]*w for _ in range(h)]
color[0][0]=1;color[h-1][w-1]=0
que=[[A[h-1][w-2],A[h-2][w-1]],[A[0][1],A[1][0]]]
heapify(que[0]);heapify(que[1])
s=[set(),set()]
for i in range(2):
    for a in que[i]:
        s[i].add(a)
        
for turn in range(1,h*w+1):
    a=heappop(que[turn%2])
    i,j=pos[a]
    color[i][j]=turn%2
    for di,dj in [(1,0),(0,1),(-1,0),(0,-1)]:
        ni,nj=i+di,j+dj
        if 0<=ni<h and 0<=nj<w and color[ni][nj]==-1 and A[ni][nj] not in s[turn%2]:
            s[turn%2].add(A[ni][nj])
            heappush(que[turn%2],(A[ni][nj]))
            
        if 0<=ni<h and 0<=nj<w and color[ni][nj]==(1-turn%2):
            print(turn)
            exit()