H, W = map(int, input().split())
A = []

for i in range(H):
    A.append(list(map(int, input().split())))

# 横方向
row_sum = []
for i in range(H):
    row_sum.append(sum(A[i]))

# 縦方向
col_sum = []
for j in range(W):
    col_sum.append(sum(a[j] for a in A))

# 斜め↘方向
down_sum = dict()
for x in range(-W+1, H):
    down_sum[x] = 0
    for i in range(H):
        if not 0 <= i - x < W:
            continue
        down_sum[x] += A[i][i-x]

# 斜め↗方向
up_sum = dict()
for x in range(0, H+W-1):
    up_sum[x] = 0
    for i in range(H):
        if not 0 <= x - i < W:
            continue
        up_sum[x] += A[i][x-i]

max_ans = 0

for i in range(H):
    for j in range(i+1, H):
        max_ans = max(max_ans, row_sum[i] + row_sum[j])

for i in range(W):
    for j in range(i+1, W):
        max_ans = max(max_ans, col_sum[i] + col_sum[j])

for k_i, v_i in down_sum.items():
    for k_j, v_j in down_sum.items():
        if k_i == k_j:
            continue
        max_ans = max(max_ans, v_i + v_j)

for k_i, v_i in up_sum.items():
    for k_j, v_j in up_sum.items():
        if k_i == k_j:
            continue
        max_ans = max(max_ans, v_i + v_j)

for i in range(H):
    for j in range(W):
        max_ans = max(max_ans, row_sum[i] + col_sum[j] - A[i][j])

for i in range(H):
    for k, v in down_sum.items():
        sub = A[i][i-k] if 0 <= i-k < W else 0
        max_ans = max(max_ans, row_sum[i] + v - sub)

for i in range(H):
    for k, v in up_sum.items():
        sub = A[i][k-i] if 0 <= k-i < W else 0
        max_ans = max(max_ans, row_sum[i] + v - sub)

for j in range(W):
    for k, v in down_sum.items():
        sub = A[k+j][j] if 0 <= j+k < H else 0
        max_ans = max(max_ans, col_sum[j] + v - sub)

for j in range(W):
    for k, v in up_sum.items():
        sub = A[k-j][j] if 0 <= k-j < H else 0
        max_ans = max(max_ans, col_sum[j] + v - sub)

for k_d, v_d in down_sum.items():
    for k_u, v_u in up_sum.items():
        if (k_d + k_u) % 2 == 0 and 0 <= (k_d + k_u) // 2 < H and 0 <= (-k_d + k_u) // 2 < W:
            sub = A[(k_d + k_u) // 2][(-k_d + k_u) // 2]
        else:
            sub = 0
        max_ans = max(max_ans, v_d + v_u - sub)

print(max_ans)