#include <bits/stdc++.h>
using namespace std;
long long int N[100000 + 100];
long long int ans = 0;
int main() {
  int n;
  cin >> n;
  int court = 0;
  int court_1 = 0;
  int court_2 = 0;
  for (int i = 0; i < n; ++i) cin >> N[i];
  for (int i = 0; i < n; ++i) {
    if (N[i] < -1) {
      ans += -1 - N[i];
      N[i] = -1;
      ++court_2;
    } else if (N[i] > 1) {
      ans += N[i] - 1;
      N[i] = 1;
      ++court_1;
    } else if (N[i] == 0) {
      court++;
    } else if (N[i] == 1) {
      court_1++;
    } else if (N[i] == -1) {
      court_2++;
    }
  }
  if (court_2 % 2 != 0) {
    if (court != 0) {
      ans += 1;
      court--;
    } else if (court == 0) {
      if (court_1 != 0) {
        court_1--;
        ans += 2;
      } else if (court_1 == 0) {
        ans += 2;
      }
    }
  }
  if (court != 0) ans += court;
  cout << ans << endl;
}
