#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long n, po = 0, ne = 0, o = 0, sum = 0;
  cin >> n;
  long long ar[n];
  for (long long i = 0; i < n; i++) {
    cin >> ar[i];
    if (ar[i] == 0)
      o++;
    else if (ar[i] <= -1)
      ne++;
    else if (ar[i] >= 1)
      po++;
  }
  for (long long i = 0; i < n; i++) {
    if (ar[i] <= -1)
      sum += (-1 - ar[i]);
    else if (ar[i] >= 1)
      sum += ar[i] - 1;
  }
  if (o) {
    sum = sum + o;
  } else if (!o && ne % 2 == 1) {
    sum += 2;
  }
  cout << sum;
}
