def maximize_sum(N, M, table):
    max_sum = float('-inf')

    for row_mask in range(1 << N):
        for col_mask in range(1 << M):
            flipped_table = [list(row) for row in table]

            # Flip rows based on row_mask
            for i in range(N):
                if (row_mask & (1 << i)) != 0:
                    for j in range(M):
                        flipped_table[i][j] *= -1

            # Flip columns based on col_mask
            for j in range(M):
                if (col_mask & (1 << j)) != 0:
                    for i in range(N):
                        flipped_table[i][j] *= -1

            # Calculate the sum of elements in the modified table
            current_sum = sum(sum(row) for row in flipped_table)
            max_sum = max(max_sum, current_sum)

    return max_sum


# Read input from the file
with open("flip.in", "r") as file:
    N, M = map(int, file.readline().split())
    table = [list(map(int, file.readline().split())) for _ in range(N)]

# Calculate the maximum sum
result = maximize_sum(N, M, table)

# Write the result to the output file
with open("flip.out", "w") as file:
    file.write(str(result) + "\n")