def bejar(x,y,size):
    sum=0
    for i in range(y,y+size):
        sum=sum+a[x][i]
        if size>1:
            sum=sum+a[x+size-1][i]
    for i in range(x+1,x+size-1):
        sum=sum+a[i][y]
        if size>1:
            sum=sum+a[i][y+size-1]
    return sum
    
n=int(input(""))
a=[]
for i in range(0,n):
    a.append([])
    s=input("")
    prop=s.split(" ")
    for j in range(0,n):
        a[i].append(int(prop[j]))
max=-32000
for size in range(1,n+1):
    for sx in range(0,n-size+1):
        for sy in range(0,n-size+1):
            temp=bejar(sx,sy,size)
            if temp>max:
                max=temp
print(max)