#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, a, dmo, dpo;
  cin >> n;
  long long cntneg = 0, cntzero = 0, cost = 0;
  for (int i = 0; i < n; i++) {
    cin >> a;
    if (a == 0) {
      cntzero++;
      continue;
    }
    if (a < 0) cntneg++;
    dmo = abs(a + 1);
    dpo = abs(a - 1);
    if (dpo < dmo)
      cost += dpo;
    else
      cost += dmo;
  }
  cost += cntzero;
  if (cntneg % 2)
    if (cntzero == 0) cost += 2;
  cout << cost << endl;
  return 0;
}
