'''
> https://www.codingame.com/ide/1850615487c96262f26bd2d508cb46b18cc23557
@author: olivier.massot, 2019
'''
import sys
from copy import deepcopy

# w, h = [int(i) for i in input().split()]
# rows = [[int(x) for x in  input().split()] for _ in range(h)]

w,h=2,2

rows = [[-1,99],
        [0,2]
        ]

def findMaxSubmatrix(matrix, height, width):
    nrows = len(matrix)
    ncols = len(matrix[0])           
    cumulative_sum = deepcopy(matrix)

    for r in range(nrows):
        for c in range(ncols):
            if r == 0 and c == 0:
                cumulative_sum[r][c] = matrix[r][c]
            elif r == 0:
                cumulative_sum[r][c] = cumulative_sum[r][c-1] + matrix[r][c]
            elif c == 0:
                cumulative_sum[r][c] = cumulative_sum[r-1][c] + matrix[r][c]
            else:
                cumulative_sum[r][c] = cumulative_sum[r-1][c] + cumulative_sum[r][c-1] - cumulative_sum[r-1][c-1] + matrix[r][c]

    best = 0

    for r1 in range(nrows):
        for c1 in range(ncols):
            r2 = r1 + height - 1
            c2 = c1 + width - 1
            if r2 >= nrows or c2 >= ncols:
                continue
            if r1 == 0 and c1 == 0:
                sub_sum = cumulative_sum[r2][c2]
            elif r1 == 0:
                sub_sum = cumulative_sum[r2][c2] - cumulative_sum[r2][c1-1]
            elif c1 == 0:
                sub_sum = cumulative_sum[r2][c2] - cumulative_sum[r1-1][c2]
            else:
                sub_sum = cumulative_sum[r2][c2] - cumulative_sum[r1-1][c2] - cumulative_sum[r2][c1-1] + cumulative_sum[r1-1][c1-1]
            if best < sub_sum:
                best = sub_sum
    return best

print(findMaxSubmatrix(rows,h,w))