m, n = map(int, input().split())
a = [[0] * n] * m
for i in range(m):
    a[i] = input().split(" ")
    a[i] = [int(j) for j in a[i]]
sums = 0
for i in range(m):
    for j in range(n):
        if i == 0 or j == 0 or i == m - 1 or j == n - 1:
            sums = sums + a[i][j]
print(sums)