#include <iostream>
#include <fstream>

using namespace std;

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

int main(){
    int n, m;
    cin >> n >> m;
    int totalSum = 0;
    int sum;
    int minn;
    int x[n][m];
    for (int i = 0; i < n; ++i){
        sum = 0;
        minn = INT_MAX;
        for (int j = 0; j < m; ++j){
            cin >> x[i][j];
            if (x[i][j] < 0){
                x[i][j] *= (-1);
            }
            sum += x[i][j];
            if (minn > x[i][j]){
                minn = x[i][j];
            }


        }

        totalSum += sum + 2 * (-minn);
    }
    cout << totalSum;
    return 0;
}