#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n = 0, k = 0;
  int flag = 0;
  long long int sum = 0, product = 1;
  cin >> n;
  if (n > 0) {
    for (long long int i = 1; i <= n; i++) {
      cin >> k;
      if (k == 0) {
        sum++;
        flag = 1;
      }
      if (k >= 1) {
        sum = sum + k - 1;
        product *= 1;
      }
      if (k <= -1) {
        sum = sum - k - 1;
        product *= -1;
      }
    }
    if ((product < 0) && (flag == 0)) sum += 2;
    cout << sum;
  } else
    cout << "0";
}
