#include <bits/stdc++.h>
using namespace std;
int main() {
  int t = 1;
  while (t--) {
    int n;
    cin >> n;
    int arr[n];
    long long int sum = 0;
    for (int i = 0; i < n; i++) cin >> arr[i];
    for (int i = 0; i < n; i++) {
      if (arr[i] == -1 || arr[i] == 0 || arr[i] == 1) {
        continue;
      } else {
        sum += (abs(arr[i]) - 1);
      }
    }
    int neg = 0, pos = 0, zer = 0;
    for (int i = 0; i < n; i++) {
      if (arr[i] == 0) zer++;
      if (arr[i] > 0) pos++;
      if (arr[i] < 0) neg++;
    }
    if (zer > 0)
      sum += zer;
    else {
      if (neg % 2 == 0)
        sum += 0;
      else
        sum += 2;
    }
    cout << sum;
  }
  return 0;
}
