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 x in range(H+W+4):
    if 0<=x<=H+1:
        dir = [(0, 1), (1, 1), (-1, 1)]
    else:
        dir = [(1, 0), (1, 1), (1, -1)]
    for dx, dy in dir:
        sco = 0
        S = set()
        if 0<=x<=H+1:
            nx = x
            ny = 0
        else:
            nx = 0
            ny = x-(H+2)
        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 x2 in range(x, H+W+4):
            if 0<=x2<=H+1:
                dir2 = [(0, 1), (1, 1), (-1, 1)]
            else:
                dir2 = [(1, 0), (1, 1), (1, -1)]
            for dx2, dy2 in dir2:
                sco2 = 0
                if 0<=x2<=H+1:
                    nx2 = x2
                    ny2 = 0
                else:
                    nx2 = 0
                    ny2 = x2-(H+2)
                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)