#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  long long int x[n];
  long long int neg = 0, zero = 0, cost = 0;
  for (int i = 0; i < n; i++) {
    cin >> x[i];
    if (x[i] > 0)
      cost = cost + x[i] - 1;
    else if (x[i] < 0) {
      cost = cost + (-x[i] - 1);
      neg++;
    } else
      zero++;
  }
  if (!zero) {
    if (neg % 2 == 0)
      cout << cost << endl;
    else
      cout << cost + 2;
  } else
    cout << cost + zero << endl;
  return 0;
}
