#include <iostream>
#include <fstream>

int main()
{
    std::ifstream fin;
    fin.open("flip.in");
    std::ofstream fout;
    fout.open("flip.out");

    int sumTot = 0;
    int N;
    int M;
    fin >> N;
    fin >> M;

    for( int i = 0 ; i< N; i++){
        int sumPos = 0;
        int sumNeg = 0;
        for( int j = 0 ; j< M; j++){
            int num;
            fin >> num;

            sumPos += num;
            sumNeg += -1*(num);
        }

        if(sumPos >= sumNeg){
            sumTot += sumPos;
        }else{
            sumTot += sumNeg;
        }

    }

    fout << sumTot;

    fin.close();
    fout.close();

    return 0;
}