#include <bits/stdc++.h>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int a[17][17];
int n, m, x, i, j, s1, s2, sum;
int main()
{
    f >> n >> m;
    for(i = 1;i <= n;i++)
        for(j = 1;j <= m;j++) f >> a[i][j];
    for(i = 1;i <= n;i++)
    {
        s1 = s2 = 0;
        for(j = 1;j <= m;j++) {s1 += a[i][j], s2 += (-a[i][j]);}
        if(s2 > s1) {for(j = 1;j <= m;j++) a[i][j] = -a[i][j];}
    }
    for(i = 1;i <= m;i++)
    {
        s1 = s2 = 0;
        for(j = 1;j <= n;j++) {s1 += a[j][i], s2 += (-a[j][i]);}
        if(s2 > s1) {for(j = 1;j <= n;j++) {a[j][i] = -a[j][i];}}
    }
    for(i = 1;i <= n;i++)
        for(j = 1;j <= m;j++) sum += a[i][j];
    g << sum;
}