#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int test = 1;
  while (test--) {
    long long int n;
    cin >> n;
    long long int a[n];
    long long int steps[n];
    long long int negSize = 0, zeroSize = 0;
    for (long long int i = 0; i < n; i++) {
      cin >> a[i];
      if (a[i] >= 1) {
        steps[i] = a[i] - 1;
      } else if (a[i] <= -1) {
        negSize++;
        steps[i] = -1 - a[i];
      } else {
        steps[i] = 1;
        zeroSize++;
      }
    }
    long long int result = 0;
    if (negSize % 2 != 0 && zeroSize == 0) {
      result = 2;
    }
    for (long long int i = 0; i < n; i++) {
      result += steps[i];
    }
    cout << result;
  }
  return 0;
}
