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

ifstream fin("flip.in");
ofstream fout("flip.out");

int N, M, i, j; 
int tabla[16][16];

int sumColoana(int tabla[16][16], int j){
    int sum = 0;
    for(i = 1; i <= N; i++)
        sum += tabla[i][j];
    return sum;
}

int sumRand(int tabla[16][16], int i){
    int sum = 0;
    for(j = 1; j <= M; j++)
        sum += tabla[i][j];
    return sum;
}

int main(){
      
    fin >> N >> M;
    
    //CITIRE TABLA
    for(i = 1; i <= N; i++)
        for(j = 1; j <= M; j++)
            fin >> tabla[i][j];


    //CALCUL COMUTATOR
    //calculul coloanelor
    for(j = 1; j <= M; j++)
        if(sumColoana(tabla, j) <= 0) 
            for(i = 1; i <= N; i++)
                tabla[i][j] *= -1;
    
    //calculul randurilor
    for(i = 1; i <= N; i++)
        if(sumRand(tabla, i) <= 0) 
            for(j = 1; j <= M; j++)
                tabla[i][j] *= -1;

    int sum = 0;
    for(i = 1; i <= N; i++)
        for(j = 1; j <= M; j++)
            sum += tabla[i][j];
    fout << sum;

    return 0;
}