#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j, k;
  cin >> n;
  int a[n];
  long long int ans = 0, neg = 0, zero = 0;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < 0) {
      neg++;
      ans += abs(a[i]) - 1;
    } else if (a[i] > 0)
      ans += abs(a[i] - 1);
    else
      zero++;
  }
  if (zero == 0) {
    if (neg % 2 == 0)
      cout << ans;
    else
      cout << ans + 2;
  } else {
    cout << ans + zero;
  }
  return 0;
}
