#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<long long> a(n);
  long long ans = 0;
  int minus = 0;
  int zero = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < 0) minus += 1;
    if (a[i] != 0)
      ans += min(abs(a[i] - 1), abs(a[i] + 1));
    else
      zero++;
  }
  if (zero == 0) {
    if (minus % 2) ans += 2;
    cout << ans << '\n';
  } else {
    cout << ans + zero << '\n';
  }
}
