#include <bits/stdc++.h>
using namespace std;

class input {

private:

    FILE* fin;
    const int sz = 10000;
    char* buff, c;
    int p;
    const char stop = char(-51);

    char read()
    {
        if (p == sz)
        {
            fread(buff, 1, sz, fin);
            p = 0;
            return buff[p++];
        }
        else
            return buff[p++];
    }

    bool digit(char c)
    {
        return c >= '0' && c <= '9';
    }

public:

    input(const char* name)
    {
        c = '-';
        buff = new char[sz];
        p = 0;
        fin = fopen(name, "r");
        fread(buff, 1, sz, fin);
    }

    void close()
    {
        fclose(fin);
    }

    void open(const char* name)
    {
        c = '-';
        p = sz;
        fin = fopen(name, "r");
    }

    bool eof()
    {
        int i = p;

        while (true)
        {
            while (i < sz && (buff[i] == ' ' || buff[i] == '\n'))
                i++;

            if (i != sz)
            {
                if (buff[i] == stop)
                    return 1;
                return 0;
            }
            else
            {
                fread(buff, 1, sz, fin);
                p = 0;
                i = 0;
            }
        }
    }

    input& operator >> (int& n)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;
        int sng = 1;

        if (c == '-')
            sng = -1, c = read();

        while (digit(c))
            n = n * 10 + (c - '0'), c = read();

        n *= sng;

        return *this;
    }

    input& operator >> (long long& n)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;
        int sng = 1;

        if (c == '-')
            sng = -1, c = read();

        while (digit(c))
            n = n * 10 + (c - '0'), c = read();

        n *= sng;

        return *this;
    }

    input& operator >> (unsigned long long& n)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;
        int sng = 1;

        if (c == '-')
            sng = -1, c = read();

        while (digit(c))
            n = n * 10 + (c - '0'), c = read();

        n *= sng;

        return *this;
    }

    input& operator >> (char& ch)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        ch = c;

        return *this;
    }

    input& operator >> (string& n)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = "";

        while (c != ' ' && c != '\n' && c != '\0')
            n += c, c = read();

        return *this;
    }

    input& operator >> (double& n)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;

        while (digit(c))
            n = n * 10 + (c - '0'), c = read();

        if (c != '.')
            return *this;

        c = read();

        double p10 = 10;

        while (digit(c))
            n = n + double(c - '0') / p10, c = read(), p10 *= 10;

        return *this;
    }

    input& operator >> (char* s)
    {
        c = read();

        while (c == ' ' || c == '\n')
            c = read();

        while (c != ' ' && c != '\n')
            *s = c, s++, c = read();

        *s = '\0';

        return *this;
    }

    void getline(string& s)
    {
        s = "";

        c = read();

        while (c == ' ')
            c = read();

        while (c != '\n')
            s += c, c = read();
    }
};
class output {

private:
    FILE* fout;
    const int sz = 10000;
    char* buff;
    int p;

    void write(char ch)
    {
        if (p == sz)
        {
            fwrite(buff, 1, sz, fout);
            p = 0;
            buff[p++] = ch;
        }
        else
            buff[p++] = ch;
    }

public:

    output(const char* name)
    {
        buff = new char[sz];
        p = 0;
        fout = fopen(name, "w");
    }

    ~output()
    {
        fwrite(buff, 1, p, fout);
    }

    output& operator << (int n)
    {
        if (n < 0)
            write('-'), n *= -1;

        if (n == 0)
        {
            write(n + '0');
            return *this;
        }

        if (n / 10 != 0)
            *this << (n / 10);

        write(('0' + (n % 10)));

        return *this;
    }

    output& operator << (long long n)
    {
        if (n < 0)
        {
            write('-');
            n *= -1;
        }

        if (n < 10)
        {
            write(n + '0');
            return *this;
        }

        *this << (n / 10);
        write((n % 10) + '0');

        return *this;
    }

    output& operator << (unsigned long long n)
    {
        if (n < 0)
        {
            write('-');
            n *= -1;
        }

        if (n < 10)
        {
            write(n + '0');
            return *this;
        }

        *this << (n / 10);
        write((n % 10) + '0');

        return *this;
    }

    output& operator << (char c)
    {
        write(c);
        return *this;
    }

    void precision(double n, int x)
    {
        *this << int(n);

        if (!x)
            return;

        write('.');

        n -= int(n);
        n *= 10;

        for (int i = 1; i <= x; i++)
        {
            *this << int(n);
            n -= int(n);
            n *= 10;
        }
    }

    output& operator << (string n)
    {
        for (auto i : n)
            write(i);
        return *this;
    }
};

input fin("number.in");
output fout("number.out");

struct group {

    long long plus, minus;

    group()
    {
        plus = minus = 0;
    }

    void add(int val)
    {
        if (val < 0)
            minus += -val;
        else
            plus += val;
    }

    void flip()
    {
        swap(plus, minus);
    }

    void modif(int val)
    {
        if (val < 0)
        {
            val = -val;
            minus -= val;
            plus += val;
        }
        else
        {
            plus -= val;
            minus += val;
        }
    }
};

int n, m, a[17][17];
group line[17], col[17];

bool fixLines()
{
    bool ok = 0;

    for (int i = 1; i <= n; i++)
        if (line[i].plus < line[i].minus)
        {
            ok = 1;
            line[i].flip();

            for (int j = 1; j <= m; j++)
                col[j].modif(a[i][j]), a[i][j] = -a[i][j];
        }

    return ok;
}

bool fixCols()
{
    bool ok = 0;

    for (int j = 1; j <= m; j++)
        if (col[j].plus < col[j].minus)
        {
            ok = 1;
            col[j].flip();

            for (int i = 1; i <= n; i++)
                line[i].modif(a[i][j]), a[i][j] = -a[i][j];
        }

    return ok;
}

int main()
{
    fin >> n >> m;

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            fin >> a[i][j], line[i].add(a[i][j]), col[j].add(a[i][j]);

    bool ok;

    do
    {
        ok = 0;
        ok |= fixLines();
        ok |= fixCols();

    } while (ok);

    long long sum = 0;

    for (int i = 1; i <= n; i++)
        sum += line[i].plus - line[i].minus;

    fout << sum;

    return 0;
}