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(0,m): for j in range(0,n): if i==0 or i ==n-1 or j==0 or j==m-1: sum_+=b[i][j] print(sum_)