#include <stdio.h>
#include <math.h>

int main()
{
        int n, m, i, j;
        long int a[17][17] = {0}, rez = 0, t = 0;
        int x[17] = {0}, y[17] = {0};
        FILE *fin, *fout;
        fin = fopen("flip.in","r");
        fout = fopen("flip.out","w");
        fscanf(fin,"%d %d",&n,&m);
        for (i = 0; i < n; i++)
        {
         t = 0;
         for (j = 0; j < m; j++)
         {
          fscanf(fin,"%ld",&a[i][j]);
          t += a[i][j];
         }
         if (t < 0) x[i] = 1;
        }
        for (i = 0; i < m; i++)
        {
         t = 0;
         for (j = 0; j < n; j++)
          t += a[j][i];
         if (t < 0) y[i] = 1;
        }
        for (i = 0; i < n; i++)
         if (x[i])
          for (j = 0; j < m; j++)
           if (a[i][j] > 0) a[i][j] *= -1;
           else a[i][j] = abs(a[i][j]);
        for (j = 0; j < m; j++)
         if (y[j])
          for (i = 0; i < n; i++)
           if (a[i][j] > 0) a[i][j] *= -1;
           else a[i][j] = abs(a[i][j]);
        for (i = 0; i < n; i++)
         for (j = 0; j < m; j++)
          rez += a[i][j];
        fprintf(fout,"%ld",rez);
        fclose(fin);
        fclose(fout);
        return 0;
}