#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  long long x, total = 0, cnt = 0, neu = 0;
  for (int i = 0; i < n; i++) {
    cin >> x;
    if (x < 0) {
      long long steps = -1 - x;
      total += steps;
      cnt++;
    } else {
      long long steps = x - 1;
      if (x == 0) {
        steps = 1;
        neu++;
      }
      total += steps;
    }
  }
  if (cnt % 2 && neu < 1) total += 2;
  cout << total;
}
