#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  cin >> n;
  long long int a[n];
  long long int minus = 0;
  long long int plus = 0;
  long long int zero = 0;
  long long int negatives_total = 0;
  long long int total = 0;
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < 0) total += (abs(a[i]) - 1), negatives_total++;
    if (a[i] > 0) total += (a[i] - 1);
    if (a[i] == 0) zero++;
  }
  if (negatives_total % 2 && zero == 0)
    cout << total + 2 << endl;
  else {
    total += zero;
    cout << total << endl;
  }
}
