#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, m;
  cin >> n;
  long long int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  long long int odd = 0, cnt = 0;
  bool flag = false;
  for (int i = 0; i < n; i++) {
    if (a[i] == 0) {
      flag = true;
      cnt++;
    }
    if (a[i] < 0) {
      if (a[i] < 0) {
        cnt += abs(a[i]) - 1;
        odd++;
      }
    }
    if (a[i] > 0) {
      if (a[i] > 0) {
        cnt += a[i] - 1;
      }
    }
  }
  if (flag) {
    cout << cnt;
  } else {
    if ((odd + 1) % 2 == 0) {
      cout << cnt + 2;
    } else {
      cout << cnt;
    }
  }
  return 0;
}
