#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  cin >> n;
  vector<long long int> p;
  vector<long long int> z;
  vector<long long int> N;
  long long int ar[n];
  for (int i = 0; i < n; i++) {
    cin >> ar[i];
  }
  for (int i = 0; i < n; i++) {
    if (ar[i] < 0) {
      N.push_back(ar[i]);
    }
    if (ar[i] == 0) {
      z.push_back(ar[i]);
    }
    if (ar[i] > 0) {
      p.push_back(ar[i]);
    }
  }
  long long int cost = 0;
  for (int i = 0; i < N.size(); i++) {
    cost += (-1 - (N[i]));
  }
  for (int i = 0; i < p.size(); i++) {
    cost += p[i] - 1;
  }
  if (z.size() > 0) {
    cost += z.size();
  } else if (N.size() % 2 == 1) {
    cost += 2;
  }
  cout << cost << endl;
}
