H,W = map(int,input().split())
A = [[0 for _ in range(W+2)]]
for _ in range(H):
    a = [0]+list(map(int,input().split()))+[0]
    A.append(a)
A.append([0 for _ in range(W+2)])
B = []
for i in range(H+2):
    B.append((i,0))
    B.append((i,W+1))
for j in range(1,W+1):
    B.append((0,j))
    B.append((H+1,j))
ans = 0
for a in B:
    for b in B:
        y1,x1 = a
        y2,x2 = b
        for dy1 in [-1,0,1]:
            for dx1 in [-1,0,1]:
                if dy1==dx1==0:continue
                cnt = 0
                y,x = y1,x1
                C = set()
                while True:
                    if y+dy1<1 or y+dy1>H or x+dx1<1 or x+dx1>W:
                        break
                    y += dy1
                    x += dx1
                    C.add((y,x))
                    cnt += A[y][x]
                for dy2 in [-1,0,1]:
                    for dx2 in [-1,0,1]:
                        if dy2==dx2==0:continue
                        cnt1 = cnt
                        y,x = y2,x2
                        while True:
                            if y+dy2<1 or y+dy2>H or x+dx2<1 or x+dx2>W:
                                break
                            y += dy2
                            x += dx2
                            if (y,x) not in C:
                                cnt1 += A[y][x]
                        ans = max(ans,cnt1)
print(ans)