#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream in;
    ofstream out;
    in.open ("flip.in");
    out.open("flip.out");
    int N, M, **A;
    in >> N;
    in >> M;
    A = new int* [N];
    int i,j;
    for (i = 0; i < N; ++i)
    {
        A[i] = new int[M];
    }
    int sum1 = 0, sum2 = 0,sum3 = 0;
    for (i = 0; i < N; ++i)
    {
        for (j = 0; j < M; ++j)
        {
            in >> A[i][j];
        }
        for (j = 0; j < M; ++j)
        {
            sum1 = A[i][j] + sum1;
            sum2 = sum2 + (-1) * A[i][j];
        }
        if (sum2 > sum1)
        {
            for (j = 0; j < M; ++j)
            {
                A[i][j] = A[i][j] * (-1);
            }
            sum3 = sum3 + sum2;
        }
        else
        {
            sum3 = sum3 + sum1;
        }
        sum2 = 0;
        sum1 = 0;
    }

    out << sum3;

    

    out.close();
    in.close();
    return 0;
        
}