#include <bits/stdc++.h>
long long int mod(long long int n) {
  if (n < 0) {
    n = -n;
  }
  return n;
}
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  long long int a[n];
  int i;
  int pc = 0, nc = 0, c0 = 0;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] > 0) {
      pc++;
    } else if (a[i] == 0) {
      c0++;
    } else {
      nc++;
    }
  }
  long long int ans = 0;
  if ((nc % 2) && (c0 == 0)) {
    ans = ans + 2;
  }
  for (i = 0; i < n; i++) {
    if (a[i] >= 0)
      ans = ans + (mod(a[i] - 1));
    else
      ans = ans + (mod(a[i] + 1));
  }
  cout << ans;
  return 0;
}
