#include <bits/stdc++.h>
using namespace std;
int n, men = 0, pluss = 0, nol = 0;
long long a, ans = 0;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a;
    if (a < 0) {
      ans += (-1 - a);
      men++;
    } else if (a > 0) {
      ans += (a - 1);
      pluss++;
    } else {
      nol++;
    }
  }
  if (nol > 0) {
    cout << ans + nol << endl;
  } else {
    if (men % 2 == 0) {
      cout << ans << endl;
    } else {
      cout << ans + 2 << endl;
    }
  }
}
