m,n = input().split() m,n=int(m),int(n) b=[] sum=0 sum1=0 sum2=0 for x in range(m): a=list(map(int,input().split())) b.append(a) for i in range(0,m): for j in range(0,n): sum1 += b[i][j] for i in range(1, m-1): for j in range(1,n-1): sum2 += b[i][j] sum=sum1-sum2 print(sum)