from itertools import product
h,w = map(int,input().split())
a = [[0]*(w+3)]+[[0]+list(map(int,input().split()))+[0,0] for _ in range(h)]+[[0]*(w+3),[0]*(w+3)]
s = []; ans = 0
for x in range(h+2):
    for dx in range(-1,2):
        px = x+dx; py = 1; t = set()
        while a[px][py]: t.add((px,py)); px += dx; py += 1
        s.append(t)
for y in range(w+2):
    for dy in range(-1,2):
        px = 1; py = y+dy; t = set()
        while a[px][py]: t.add((px,py)); px += 1; py += dy
        s.append(t)
for si in s:
    for sj in s:
        ans = max(ans,sum(a[x][y] for x,y in si|sj))
print(ans)