n,m=input().split() n,m=int(n),int(m) sum_=0 b=[] for i in range(n): a=list(map(int,input().split())) b.append(a) for i in range(n): for j in range(m): if i == 0 or i == n - 1 or j == 0 or j == m - 1: sum_ += b[i][j] print(sum_)