m, n = map(int, input().split()) perimeter_sum = 0 matrix = [] for i in range(m): row = list(map(int, input().split())) matrix.append(row) perimeter_sum += row[0] + row[-1] # 计算第一列和最后一列的和 # 计算第一行和最后一行的和 perimeter_sum += sum(matrix[0]) + sum(matrix[-1]) print(perimeter_sum)