H,W = map(int,input().split())
A = [[0 for _ in range(W+2)]]
for _ in range(H):
    a = [0]+list(map(int,input().split()))
    A.append(a)
C = []
for i in range(1,H+1):
    y = i
    x = 1
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x+1>W:break
        x += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = i
    x = 1
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x+1>W or y+1>H:break
        x += 1
        y += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = i
    x = 1
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x+1>W or y-1<1:break
        x += 1
        y -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = i
    x = W
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x-1<1:break
        x -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = i
    x = W
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x-1<1 or y+1>H:break
        x -= 1
        y += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = i
    x = W
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if x-1<1 or y-1<1:break
        x -= 1
        y -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
for j in range(1,W+1):
    y = 1
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y+1>H:break
        y += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = 1
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y+1>H or x+1>W:break
        y += 1
        x += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = 1
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y+1>H or x-1<1:break
        y += 1
        x -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = H
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y-1<1:break
        y -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = H
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y-1<1 or x+1>W:break
        y -= 1
        x += 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
    y = H
    x = j
    cnt = A[y][x]
    trace = set([(y,x)])
    while True:
        if y-1<1 or x-1<1:break
        y -= 1
        x -= 1
        cnt += A[y][x]
        trace.add((y,x))
    C.append((trace,cnt))
ans = 0
for a,cnt1 in C:
    for b,cnt2 in C:
        c = a&b
        cnt3 = 0
        for y,x in c:
            cnt3 += A[y][x]
        ans = max(ans,cnt1+cnt2-cnt3)
print(ans)