m,n = input().split() m,n = int(m),int(n) a =[] for x in range(m): b = list(map(int,input().split())) a.append(b) res = 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: res = res + a[i][j] #边缘元素 print(res)