h,w=map(int,input().split())
a=[list(map(int,input().split())) for i in range(h)]
v=[[0]*w for i in range(h)]
v[0][0]=1
v[h-1][w-1]=2
from heapq import heappush,heappop
q1=[]
heappush(q1,(a[1][0],1,0))
heappush(q1,(a[0][1],0,1))
q2=[]
heappush(q2,(a[h-2][w-1],h-2,w-1))
heappush(q2,(a[h-1][w-2],h-1,w-2))
for i in range(1,h*w+1):
  if i%2:
    while len(q1)>0 and v[q1[0][1]][q1[0][2]]!=0:
      heappop(q1)
    if len(q1)==0:
      print(i-1)
      exit()
    z,x,y=heappop(q1)
    v[x][y]=1
    dx,dy=1,0
    for _ in range(4):
      xx,yy=x+dx,y+dy
      dx,dy=-dy,dx
      if 0<=xx<h and 0<=yy<w:
        if v[xx][yy]==0:
          heappush(q1,(a[xx][yy],xx,yy))
        if v[xx][yy]==2:
          print(i)
          exit()
  else:
    while len(q2)>0 and v[q2[0][1]][q2[0][2]]!=0:
      heappop(q2)
    if len(q2)==0:
      print(i-1)
      exit()
    z,x,y=heappop(q2)
    v[x][y]=2
    dx,dy=1,0
    for _ in range(4):
      xx,yy=x+dx,y+dy
      dx,dy=-dy,dx
      if 0<=xx<h and 0<=yy<w:
        if v[xx][yy]==0:
          heappush(q2,(a[xx][yy],xx,yy))
        if v[xx][yy]==1:
          print(i)
          exit()