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