import sys
input = sys.stdin.readline
H, W = map(int, input().split())
A = [list(map(int, input().split())) for _ in range(H)]
ans = 0

for dx, dy in [(0, 1), (1, 0), (1, 1), (-1, 1)]:
    if dx==0:
        rng = range(1, H+1)
    elif dy==0:
        rng = range(1, W+1)
    else:
        rng = range(H+W+4)
    for x in rng:
        sco = 0
        S = set()
        if dx==0:
            nx = x
            ny = 0
        elif dy==0:
            nx = 0
            ny = x
        elif dx==1:
            nx = x-(W+2)
            ny = 0
        else:
            nx = x
            ny = 0
        nx+=dx
        ny+=dy
        if dx==0 or dy==0:
            while 1<=nx<=H and 1<=ny<=W:
                sco += A[nx-1][ny-1]
                S.add((nx, ny))
                nx+=dx
                ny+=dy
        else:
            while 1<=ny<=W:
                if 1<=nx<=H and 1<=ny<=W:
                    sco += A[nx-1][ny-1]
                    S.add((nx, ny))
                nx+=dx
                ny+=dy

        for dx2, dy2 in [(0, 1), (1, 0), (1, 1), (-1, 1)]:
            if dx2==0:
                rng2 = range(1, H+1)
            elif dy2==0:
                rng2 = range(1, W+1)
            else:
                rng2 = range(H+W+4)
            for x2 in rng2:
                sco2 = 0
                if dx2==0:
                    nx2 = x2
                    ny2 = 0
                elif dy2==0:
                    nx2 = 0
                    ny2 = x2
                elif dx2==1:
                    nx2 = x2-(W+2)
                    ny2 = 0
                else:
                    nx2 = x2
                    ny2 = 0
                nx2+=dx2
                ny2+=dy2
                if dx2==0 or dy2==0:
                    while 1<=nx2<=H and 1<=ny2<=W:
                        if (nx2, ny2) not in S:
                            sco2 += A[nx2-1][ny2-1]
                        nx2+=dx2
                        ny2+=dy2
                else:
                    while 1<=ny2<=W:
                        if 1<=nx2<=H and 1<=ny2<=W:
                            if (nx2, ny2) not in S:
                                sco2 += A[nx2-1][ny2-1]
                        nx2+=dx2
                        ny2+=dy2

                ans = max(ans, sco+sco2)
print(ans)