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