【蓝桥杯 每天一道算法题】跳跃

# https://www.lanqiao.cn/problems/553/learning/?page=2&first_category_id=1&sort=students_count
# dp直接秒
import copy

r, c = map(int, input().split())
reward = [[] for _ in range(r)]
for i in range(r):
    reward[i] = list(map(int, input().split()))
dp = copy.deepcopy(reward)
for i in range(r):
    for j in range(c):
        if i == 0 and j == 0:
            continue
        dp[i][j] = - 1e4 - 1
        for k in range(4):
            for l in range(4):
                if k == 0 and l == 0:
                    continue
                if k + l > 3:
                    break
                if i - k < 0 or j - l < 0:
                    break
                dp[i][j] = max(dp[i][j], dp[i - k][j - l] + reward[i][j])
# print(dp)
print(dp[-1][-1])