def find_max_sum_submatrix(matrix):
    rows = len(matrix)
    columns = len(matrix[0])
    temp = [[0 for i in range(rows+1)] for j in range(columns+1)]
    for i in range(rows+1):
        for j in range(columns+1):
            if i == 0 or j == 0:
                temp[i][j] = 0
            else:
                temp[i][j] = temp[i-1][j] + temp[i][j-1] - temp[i-1][j-1] + matrix[i-1][j-1]

    max_sum = -1000000
    for i in range(rows):
        for j in range(i, rows):
            for m in range(columns):
                for n in range(m, columns):
                    submatrix_sum = temp[j+1][n+1] - temp[j+1][m] - temp[i][n+1] + temp[i][m]
                    if submatrix_sum > max_sum:
                        max_sum = submatrix_sum

    return max_sum


row_size, col_size = input().split()
row_size = int(row_size)
col_size = int(col_size)
matrix = [[0 for i in range(col_size)] for j in range(row_size)]
count = 0

for i in range(row_size):
    row = [char for char in input().split()]
    for j in range(col_size):
        matrix[i][j] = int(row[j])

print("Max submatrix:", find_max_sum_submatrix(matrix))