#include<fstream.h>
int main(void)
{       int mat[16][16];
	long N,M,i,j,suma=0,sumab=0,sumaf=0;
	ifstream in("flip.in");
	in>>N>>M;
	for(i=1;i<=N;i++)
	 for(j=1;j<=M;j++)
	  in>>mat[i][j];
	in.close();
	for(i=1;i<=N;i++)
		for(j=1;j<=M;j++)
		{	if(j==M)
			{for(j=1;j<=M;j++)
				{suma=suma+mat[i][j];
				mat[i][j]=mat[i][j]*-1;
				sumab=sumab+mat[i][j];}
			if(sumab<suma)
				for(j=1;j<=M;j++)
					mat[i][j]=mat[i][j]*-1;
			suma=0;sumab=0;
			}
		}
	suma=0;sumab=0;
	for(j=1;j<=M;j++)
		for(i=1;i<=N;i++)
		{	if(i==N)
			{for(i=1;i<=N;i++)
			       {suma=suma+mat[i][j];
			       mat[i][j]=mat[i][j]*-1;
			       sumab=sumab+mat[i][j];}
			 if(sumab<suma)
				for(i=1;i<=N;i++)
					mat[i][j]=mat[i][j]*-1;
			 suma=0;sumab=0;
			}
		}
	for(i=1;i<=N;i++)
		for(j=1;j<=M;j++)
			sumaf=sumaf+mat[i][j];
	ofstream out("flip.out");
	out<<sumaf;
	out.close();
	return 0;
}