#include<stdio.h>
#include<stdlib.h>


int main(){
    FILE * f;
    FILE * g;

    f = fopen("flip.in","r");
    g = fopen("flip.out","w");

    int n,m,a[17][17],i,j,s,s1,s2;

    s = 0;

    fscanf(f,"%d%d",&n,&m);

    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            fscanf(f,"%d",&a[i][j]);

    for (j=1; j<=m; j++){
        s1 = s2 = 0;
        for (i=1; i<=n; i++){
            s1 = s1 + a[i][j];
            s2 = s2 - a[i][j];
        }
        if (s2 > s1)
            for (i=1; i<=n; i++)
                a[i][j] = (-1) * a[i][j];
    }

    for (i=1; i<=n; i++){
        s1 = s2 = 0;
        for (j=1; j<=m; j++){
            s1 = s1 + a[i][j];
            s2 = s2 - a[i][j];
        }
        if (s2 > s1)
            for (j=1; j<=m; j++)
                a[i][j] = (-1) * a[i][j];
    }



    for (i = 1;i<=n;i++)
        for (j=1;j<=m;j++)
            s = s + a[i][j];

    fprintf(g,"%d",s);
return 0;

}