#include <stdio.h>
int main ( )
{
    int  i, j, n, m;
    long a[20][20], sPoz, sNeg, sMax = 0, b[20][20];
    freopen ( "flip.in", "r", stdin );
    freopen ( "flip.out", "w",stdout );
    scanf ( "%d %d", &n, &m );
    for ( i = 0; i < n ; i++ )
        for ( j = 0; j < m; j++ )
            scanf ( "%ld", &a[i][j] );
    for ( i = 0; i < n; i++ )
    {
        sPoz = 0;
        sNeg = 0;
        for ( j = 0; j < m; j++ )
            if ( a[i][j] > 0 )
                sPoz = sPoz + a[i][j];
            else
                sNeg = sNeg + a[i][j];
        sNeg = sNeg * ( -1 );
        if ( sNeg > sPoz )
            for ( j = 0 ; j < m; j++ )
                b[i][j] = a[i][j] * ( -1 );
        else
            for ( j = 0 ; j < m; j++ )
                b[i][j] = a[i][j];
    }
    for ( j = 0; j < m; j++ )
    {
        sPoz = 0;
        sNeg = 0;
        for ( i = 0; i < n; i++ )
            if ( a[i][j] > 0 )
                sPoz = sPoz + a[i][j];
            else
                sNeg = sNeg + a[i][j];
        sNeg = sNeg * ( -1 );
        if ( sNeg > sPoz )
            for ( i = 0 ; i < n; i++ )
                if ( b[i][j] == a[i][j] )
                    b[i][j] = a[i][j] * ( -1 );
    }
    for ( i = 0; i < n; i++ )
        for ( j = 0; j < m; j++ )
            sMax = sMax + b[i][j];
    printf ( "%ld", sMax );
}