a = input().split(' ')

row = int(a[0])
col = int(a[1])
L = list()
sum = 0
sum_in = 0                 #矩阵去除边缘元素之和

for i in range(row):
    k = input().split(' ')
    x = list(map(int, list(k)))
    L.append(x) 

def sum(row, col, t):      #求和
    sum = 0
    for i in range(row):
             for j in range(col):
                 sum = sum + t[i][j]
    return sum


if row < 3 | col < 3:
    pass
else:
    for i in range(1, row-1):
         for j in range(1, col-1):
              sum_in = sum_in + L[i][j]
          
print(sum(row, col, L) - sum_in)

第五个测试点RE，其他AC