#include <bits/stdc++.h>
using namespace std;
const long long N = 1e5 + 10;
long long n;
long long cnt, can, ans;
long long a[N];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    if (a[i] > 1) {
      ans += a[i] - 1;
      a[i] = 1;
    }
    if (a[i] == 0) can++;
    if (a[i] <= -1) {
      ans += abs(a[i]) - 1;
      a[i] = -1;
      cnt++;
    }
  }
  if (cnt == 0 || cnt % 2 == 0 || can > 0)
    ans += can;
  else {
    ans += 2;
  }
  cout << ans;
}
