#include <fstream>

const char* inFile = "flip.in";
const char* outFile = "flip.out";



void tryFlipLine(int numLines, int numCols, int* matrix, int lineNum)
{
    int sumPositives = 0;
    int sumNegatives = 0;

    for (int index = 0; index < numCols; ++index)
    {
        auto elem = matrix[lineNum * numCols + index];
        if (elem < 0)
        {
            sumNegatives -= elem;
        }
        else
        {
            sumPositives += elem;
        }
    }

    if (sumNegatives > sumPositives)
    {
        for (int index = 0; index < numCols; ++index)
        {
            matrix[lineNum * numCols + index] *= -1;
        }
    }
}

void tryFlipCol(int numLines, int numCols, int* matrix, int colNum)
{
    int sumPositives = 0;
    int sumNegatives = 0;

    for (int index = 0; index < numLines; ++index)
    {
        auto elem = matrix[index * numCols + colNum];
        if (elem < 0)
        {
            sumNegatives -= elem;
        }
        else
        {
            sumPositives += elem;
        }
    }

    if (sumNegatives > sumPositives)
    {
        for (int index = 0; index < numLines; ++index)
        {
            matrix[index * numCols + colNum] *= -1;
        }
    }
}

int flip(int numLines, int numCols, int* matrix)
{
    for (auto l = 0; l < numLines; ++l)
    {
        tryFlipLine(numLines, numCols, matrix, l);
    }

    for (auto c = 0; c < numCols; ++c)
    {
        tryFlipCol(numLines, numCols, matrix, c);
    }

    int sum = 0;

    for (auto i = 0; i < numLines * numCols; ++i)
    {
        sum += matrix[i];
    }

    return sum;
}


int main()
{
    int numLines = 0;
    int numCols = 0;

    std::ifstream readFile(inFile);
    if (!readFile) return -1;

    readFile >> numLines >> numCols;

    int* matrix = new int[numLines*numCols];


    for (int index = 0; index < numLines * numCols; ++index)
    {
        readFile >> matrix[index];
    }

    auto sum = flip(numLines, numCols, matrix);


    return 0;
}