#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n;
  long long ans = 0;
  int negatives = 0;
  int zeroes = 0;
  int x;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x;
    if (x == -1) {
      negatives++;
      continue;
    } else if (x == 1)
      continue;
    if (x < 0) {
      ans += abs(x + 1);
      negatives++;
    } else if (x == 0)
      zeroes++;
    else {
      ans += x - 1;
    }
  }
  if (negatives % 2 != 0 && zeroes > 0) {
    ans++;
    zeroes--;
  } else if (negatives % 2 != 0) {
    ans += 2;
    negatives--;
  }
  ans += zeroes;
  cout << ans << endl;
  return 0;
}
