#include <bits/stdc++.h>
using namespace std;
int main() {
  long long y, n = 0, p = 0, o = 0, count = 0;
  int x;
  cin >> x;
  while (x--) {
    cin >> y;
    if (y < 0) n++;
    if (y == 0) o++;
    count += abs(abs(y) - 1);
  }
  if (o == 0 && n % 2 == 1) count = count + 2;
  cout << count;
}
