#include <fstream>
using namespace std;ifstream f("flip.in"); ofstream g("flip.out"); short int N,M; int v[17][17];
void comutl(short int x) {short int y; for (y=1;y<=M;y++){v[x][y]=-v[x][y];};};
void comutc(short int y) {short int x; for (x=1;x<=N;x++){v[x][y]=-v[x][y];};};
int main() { short int i,j; int sm,sp; unsigned long long st=0;
f>>N>>M; for (i=1;i<=N;i++){sp=0;sm=0; for (j=1;j<=M;j++){f>>v[i][j]; if (v[i][j]>0){sp=sp+v[i][j];} else {sm=sm+v[i][j];};}; if (-sm>sp){comutl(i);};};
for (j=1;j<=M;j++){sp=0;sm=0; for (i=1;i<=N;i++){if (v[i][j]>0){sp=sp+v[i][j];} else {sm=sm+v[i][j];};}; if (-sm>sp){comutc(j);};};
for (i=1;i<=N;i++) for (j=1;j<=M;j++) {st=st+v[i][j];};
g<<st<<'\n';
return 0;};