#include <iostream>
#include <fstream>
using namespace std;
int main(){
    ifstream f("flip.in");
    int n, m;
    f >> n >> m;
    int A[16][16];
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++)
            f >> A[i][j];
    }
    for(int i = 0;i < n; i++){
        int sumaNrPoz = 0, sumaNrNeg = 0;
        for(int j = 0; j < m; j++){
            if(A[i][j] > 0) sumaNrPoz+=A[i][j];
            else sumaNrNeg+=(-1)*A[i][j];
        }
        if(sumaNrNeg > sumaNrPoz){
           for(int j = 0; j < m; j++){
                A[i][j] = -1 * A[i][j];
            }
        }
    }
    for(int j = 0;j < m; j++){
        int sumaNrPoz = 0, sumaNrNeg = 0;
        for(int i = 0; i < n; i++){
            if(A[i][j] > 0) sumaNrPoz+=A[i][j];
            else sumaNrNeg+=(-1)*A[i][j];
        }
        if(sumaNrNeg > sumaNrPoz){
           for(int i = 0; i < m; i++){
                A[i][j] = -1 * A[i][j];
            }
        }
    }
    int suma = 0;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++)
            suma+=A[i][j];
    }
    ofstream g("flip.out");
    g << suma;
}