#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  vector<long long> v(n);
  long long neg = 0;
  long long cnt0 = 0;
  for (int i = 0; i < n; i++) {
    cin >> v[i];
    if (v[i] < 0) {
      neg++;
    }
    if (v[i] == 0) cnt0++;
  }
  long long cnt = 0;
  for (int i = 0; i < n; i++) {
    cnt += abs(abs(v[i]) - 1);
  }
  if (neg % 2 == 0 || cnt0 >= 1) {
    cout << cnt;
  } else {
    cout << cnt + 2;
  }
}
