import sys
input = sys.stdin.readline
def read_values(): return tuple(map(int, input().split()))
def read_list(): return list(read_values())

def main():
    h,w=read_values()
    a=[]
    for _ in range(h):
        a.append(read_list())
    ans=0
    st=set()
    for i in range(-1,h+1):
        st.add((i,-1))
        st.add((i,w))
    for i in range(-1,w+1):
        st.add((-1,i))
    d=[(0,1),(1,-1),(1,0),(1,1)]
    for fx,fy in st:
        for dx,dy in d:
            tmp=0
            x=fx
            y=fy
            visit=set()
            while True:
                x+=dx
                y+=dy
                if x<0 or y<0 or x>=h or y>=w:
                    break
                if not (x,y) in visit:
                    tmp+=a[x][y]
                visit.add((x,y))
            for fx2,fy2 in st:
                for dx2,dy2 in d:
                    tmp2=tmp
                    x=fx2
                    y=fy2
                    visit2=visit.copy()
                    while True:
                        x+=dx2
                        y+=dy2
                        if x<0 or y<0 or x>=h or y>=w:
                            break
                        if not (x,y) in visit2:
                            tmp2+=a[x][y]
                        visit2.add((x,y))
                    ans=max(ans,tmp2)
    print(ans)


if __name__ == "__main__":
    main()