func_code_string: #include <bits/stdc++.h>   using namespace std;   const int size = 508;   int num[size];   int Abs(int x) { return x > 0 ? x : -x; }   int main() {     int n, sum, m, i, x, L, R, c, t, v, up;     cin >> n;     sum = m = 0;     up = 1000000;     for (i = 1; i <= 2 * n - 1; i++) {       cin >> num[i];       if (num[i] < 0) m++;       sum += Abs(num[i]);       if (up > Abs(num[i])) up = Abs(num[i]);     }     if (n & 1) {       cout << sum << endl;       return 0;     }     if (m & 1) {       cout << sum - 2 * up << endl;     } else       cout << sum << endl;     return 0;   }   