#include <bits/stdc++.h>
#define for0(i, n) for(int i = 0; i < n; i++)
#define for1(i, n) for(int i = 1; i <= n; i++)
#define pb push_back
#define mp make_pair
#define all(v) v.begin(), v.end()
#define V vector<int>
#define VP vector<pair<int, int> >
#define FASTIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
using namespace std;
#ifdef _WIN32
#include <windows.h>
#define print(x) PRINT(x, #x)
template<typename T> inline const void PRINT(T VARIABLE, string NAME)
{
#ifndef ONLINE_JUDGE /// ONLINE_JUDGE IS DEFINED ON CODEFORCES
    HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
    SetConsoleTextAttribute(hConsole, 10);
    cerr << NAME << " = " << VARIABLE;
    SetConsoleTextAttribute(hConsole, 7);
    cerr << '\n';
#endif
}
#else
#define print(x) 0
#endif
typedef long long ll;
typedef unsigned long long ull;
const ll INFLL = 2 * (ll)1e18 + 100;
const int INFINT = 2 * (int)1e9 + 100;
const double PI = atan(1) * 4;
const double EPS = 1e-12;
const int SEED = 1e3 + 7;

const int MOD = 1e9 + 7; /// careful here (7 or 9, 66.. etc)
const int NMAX = 1e6 + 5;

ifstream fin("flip.in");
ofstream fout("flip.out");
#define cin fin
#define cout fout

int n, m;
int mat[20][20];
int sol = -INFINT;
void backtracking(vector<int> mul, int start)
{
    int matcpy[20][20];
    for1(i, n) for1(j, m) matcpy[i][j] = mat[i][j];
    for(auto i: mul) for1(j, m) matcpy[i][j] *= -1;
    for1(j, m)
    {
        int sum_neg = 0, sum_pos = 0;
        for1(i, n)
        if(mat[i][j] < 0) sum_neg += -matcpy[i][j];
        else sum_pos += matcpy[i][j];
        if(sum_neg > sum_pos) for1(i, n) matcpy[i][j] *= -1;
    }
    int sum = 0;
    for1(i, n) for1(j, m) sum += matcpy[i][j];
    sol = max(sol, sum);

    for(int i = start; i <= n; i++)
    {
        mul.pb(i);
        backtracking(mul, i + 1);
        mul.pop_back();
    }
}

int main()
{
    FASTIO;
    cin >> n >> m;
    for1(i, n) for1(j, m) cin >> mat[i][j];

    vector<int> temp;
    backtracking(temp, 1);
    cout << sol;

    return 0;
}