#include <bits/stdc++.h>   using namespace std;   int a[1000000], l[1000000], r[1000000];   int main() {     int n;     cin >> n;     int minn = 10000000;     int kol = 0;     int ans = 0;     int m = 2 * n - 1;     for (int i = 0; i < m; i++) {       cin >> a[i];       if (a[i] < 0) {         kol++;         a[i] = -a[i];       }       ans += a[i];       if (a[i] < minn) minn = a[i];     }     if (n % 2 == 1)       cout << ans << endl;     else {       if (kol % 2 == 0)         cout << ans << endl;       else         cout << ans - 2 * minn << endl;     }   }   