#include <stdio.h>

#define col(x) scol[x][0]
#define colf(x) scol[x][1]
#define lin(x) slin[x][0]
#define linf(x) slin[x][1]

#define flip_lin(x) for(gi=0; gi<m; gi++) {a[x][gi] = -a[x][gi];}
#define flip_col(x) for(gi=0; gi<n; gi++) {a[gi][x] = -a[gi][x];}

#define SIZE 16
int a[SIZE][SIZE], f[SIZE + 1];
int n, m, gi, s;

void suma() {
	int i, j, suma = 0;
	for(i=0; i<n; i++)
		for(j=0; j<m; j++)
			suma += f[i]*a[i][j];
	if(suma > s)
		s = suma;
}

void back(int lin) {
	if(lin == n)
		suma();
	else {
		f[lin] = 0;
		back(lin+1);
		f[lin] = 1;
		back(lin+1);
	}
}

int main(int argc, char **argv) {
	int i, j;
	FILE *f = fopen("flip.in", "r");
	if(f == NULL) { fclose(f); printf("eroare la citire!\n"); return -1; };
	fscanf(f, "%d", &n);
	fscanf(f, "%d", &m);
	for(i=0; i<n; i++)
		for(j=0; j<m; j++)
			fscanf(f, "%d", &a[i][j]);
	fclose(f);
	
	back(0);
	
	f = fopen("flip.out", "w");
	fprintf(f, "%d\n", s);
	fclose(f);
	
	return 0;
}