def sum_of_perimeter_elements(matrix): # 计算边缘元素的和 perimeter_sum = 0 m, n = len(matrix), len(matrix[0]) for i in range(m): for j in range(n): if i == 0 or i == m - 1 or j == 0 or j == n - 1: perimeter_sum += matrix[i][j] return perimeter_sum # 读取矩阵的行数和列数 m, n = map(int, input().split()) # 初始化矩阵 matrix = [] # 读取矩阵的元素 for _ in range(m): matrix.append(list(map(int, input().split()))) # 调用函数计算边缘元素的和 perimeter_sum = sum_of_perimeter_elements(matrix) # 输出结果 print(perimeter_sum)