# include <fstream>

using namespace std;

int main(){

    ifstream in("flip.in");
    ofstream out("flip.out");

    int n,m,sum,s,mat[16][16],i,j,z,h;

    in>>n>>m;

    for(i = 0 ; i < n ; ++i )
        for( j = 0 ; j < m ; ++j)
            in>>mat[i][j];

    sum = -1 ;
    z = -1;
    h = 0;

    while( 1 ){
        ++z;
        if( z == n ) z = 0 , ++h;
        if( h == m ) break;
        for( j = 0 ; j < m ; ++j ) mat[z][j] *= -1;
        for( i = 0 ; i < n ; ++i ) mat[i][h] *= -1;
        s = 0;
        for( i = 0 ; i < n ; ++i )
            for( j = 0 ; j < m ; ++j ) s += mat[i][j];
        if(s > sum) sum = s;
        for( j = 0 ; j < m ; ++j ) mat[z][j] *= -1;
        for( i = 0 ; i < n ; ++i ) mat[i][h] *= -1;
    }

    out<<sum;

    in.close();
    out.close();
    return 0;
}