#include <fstream>
using namespace std;
int main()
{
    int n,m,s1=0,i,j,x[100][100],s2=0;
    ifstream cin("flip.in");
    ofstream cout("flip.out");
    cin>>n>>m;
    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
        {
            cin>>x[i][j];
            x[i][j]=x[i][j]*(-1);
            if(x[i][j]>0)
                s1+=x[i][j];
            else
                s2+=x[i][j]*(-1);
        }
        if(s1>s2)
            cout<<s1;
        else
            cout<<s2;
    return 0;
}