import sys
input = sys.stdin.readline
h,w=map(int,input().split())
A=[list(map(int,input().split())) for _ in range(h)]
d=[(-1,-1),(-1,0),(-1,1),(0,-1),(0,1),(1,-1),(1,0),(1,1)]
ans=0
l=[]
for i in range(w+1):
  l.append((0,i))
for i in range(h+1):
  l.append((i,w+1))
for i in range(w+1):
  l.append((h+1,w+1-i))
for i in range(h+1):
  l.append((h+1-i,0))
for i,j in l:
  for ii,jj in l:
    for dx,dy in d:
      for ddx,ddy in d:
        se=set()
        nowi=i+dx
        nowj=j+dy
        tmp=0
        while 1<=nowi<=h and 1<=nowj<=w:
          if (nowi,nowj) not in se:
            tmp+=A[nowi-1][nowj-1]
          se.add((nowi,nowj))
          nowi+=dx
          nowj+=dy
        nowi=ii+ddx
        nowj=jj+ddy
        while 1<=nowi<=h and 1<=nowj<=w:
          if (nowi,nowj) not in se:
            tmp+=A[nowi-1][nowj-1]
          se.add((nowi,nowj))
          nowi+=ddx
          nowj+=ddy  
        ans=max(ans,tmp)
print(ans)