# 斜めがあるからややこしい
# 方向を左・上からに限定する

H, W = map(int, input().split())
A = [list(map(int, input().split())) for _ in range(H)]

n1 = [[] for _ in range(H+W-1)]
hwmin = -(W-1)
hwmax = H-1
period = hwmax - hwmin + 1
n2 = [[] for _ in range(period)]

for i in range(H):
    for j in range(W):
        n1[i+j].append((i,j))
        n2[(i-j) - hwmin].append((i,j))

S = n1 + n2

# yoko
for i in range(H):
    tmp = []
    for j in range(W):
        tmp.append((i,j))
    S.append(tmp)

# tate
for j in range(W):
    tmp = []
    for i in range(H):
        tmp.append((i,j))
    S.append(tmp)

num = len(S)
ans = 0

for s0 in range(num):
    for s1 in range(s0+1,num):
        g = set()
        tmp = 0
        for i,j in S[s0]:
            if (i,j) not in g:
                tmp += A[i][j]
                g.add((i,j))
    
        for i,j in S[s1]:
            if (i,j) not in g:
                tmp += A[i][j]
                g.add((i,j))

        ans = max(ans, tmp)

print(ans)