row,col = input().split() row = int(row) col = int(col) a=[] for i in range(row): tmp=input().split() tmp=[int(x) for x in tmp] a.append(tmp) res=0 for i in range(row): for j in range(col): if i==0 or i ==row-1: res = res + a[i][j] elif j == 0 or j == col - 1: res = res +a[i][j] print(res)