14500.py

# 테트로미노
import sys

N, M = map(int, sys.stdin.readline().split())

Paper = []


for _ in range(N):
    line = list(map(int, sys.stdin.readline().split()))
    Paper.append(line)


directions = [("L", -1, 0), ("R", 1, 0), ("U", 0, -1), ("D", 0, 1)]
reverse_Dirs = {"L": "R", "R": "L", "U": "D", "D": "U"}


sum_list = []


def add(shape, sum_num, cnt, x, y):
    if x >= M or x < 0:
        return
    if y >= N or y < 0:
        return

    sum_num += Paper[y][x]
    cnt += 1
    if cnt == 4:
        sum_list.append(sum_num)
        return

    rev_dir = reverse_Dirs[shape[-1]]
    if cnt == 2:
        if shape == "R":
            if x + 1 < M:
                add(shape, sum_num + Paper[y][x + 1], 3, x, y - 1)
                add(shape, sum_num + Paper[y][x + 1], 3, x, y + 1)
        elif shape == "D":
            if y + 1 < N:
                add(shape, sum_num + Paper[y + 1][x], 3, x - 1, y)
                add(shape, sum_num + Paper[y + 1][x], 3, x + 1, y)

    for dir, xp, yp in directions:
        if dir == rev_dir:
            continue

        add(shape + dir, sum_num, cnt, x + xp, y + yp)


for i in range(M):
    for j in range(N):
        add("R", Paper[j][i], 1, i + 1, j)
        add("D", Paper[j][i], 1, i, j + 1)
        add("L", Paper[j][i], 1, i - 1, j)
        add("U", Paper[j][i], 1, i, j - 1)

print(max(sum_list))