#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i;
  cin >> n;
  long long int arr[n], count0 = 0, count1 = 0, count_ve = 0, count = 0;
  for (i = 0; i < n; i++) {
    cin >> arr[i];
    if (arr[i] == 0) count0++;
    if (arr[i] > 1) {
      count = count + arr[i] - 1;
      arr[i] = 1;
    } else if (arr[i] < -1) {
      count = count - arr[i] - 1;
      arr[i] = -1;
    }
    if (arr[i] == 1) count1++;
    if (arr[i] == -1) count_ve++;
  }
  if (count_ve % 2 == 1) {
    if (count0 > 0) {
      count = count + count0;
    } else {
      count = count + 2;
    }
  } else if (count_ve % 2 == 0) {
    if (count0 > 0) count = count + count0;
  }
  cout << count << endl;
  return 0;
}
