def main(): r, c = map(int, input().split()) mat = [] for i in range(r): row = list(map(int, input().split())) mat.append(row) s = 0 for num in mat[0]: s += num for num in mat[-1]: s += num for i in range(1, r-1): s += mat[i][0] s += mat[i][-1] print(s) if __name__ == "__main__": main()