#include <bits/stdc++.h>
using namespace std;
const double PI = 2 * acos(0.0);
const long long MOD = 1e9 + 7;
int main() {
  int n;
  cin >> n;
  int arr[n + 10];
  vector<int> neg, pos;
  long long ans = 0, zero = 0;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
    if (arr[i] < 0) {
      neg.push_back(arr[i]);
    } else {
      if (arr[i] == 0) {
        zero++;
      } else {
        ans += (arr[i] - 1);
      }
    }
  }
  sort(neg.begin(), neg.end());
  for (int i = 0; i < neg.size(); i += 2) {
    if (i + 1 == neg.size()) {
      ans += abs(-1 - neg[i]);
      if (zero > 0) {
        ans += 1;
        zero--;
      } else {
        ans += 2;
      }
    } else {
      ans += abs(-1 - (neg[i]));
      ans += abs(-1 - (neg[i + 1]));
    }
  }
  cout << ans + zero << endl;
  return 0;
}
