#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int i;
  long long int a[n];
  unsigned long long int x = 0;
  int xero = 0;
  int poop = 0;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < 0) poop += 1;
    if (a[i] == 0)
      xero++;
    else
      x += abs(a[i]) - 1;
  }
  if (poop % 2 == 1) {
    if (xero) {
      x++;
      xero--;
    } else
      x += 2;
  }
  x += xero;
  cout << x << endl;
}
