#include <bits/stdc++.h>
using namespace std;
int main() {
  long long i, j, k, l, m, n;
  long long negs = 0, pos = 0, zero = 0, NN = 0, PP = 0;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> l;
    if (l < 0) {
      NN++;
      negs += l;
    } else if (l > 0) {
      PP++;
      pos += l;
    } else
      zero++;
  }
  long long ans = max(0ll, pos - PP);
  negs = abs(negs);
  ans += (negs - NN);
  if (zero == 0) {
    if (NN % 2) ans += 2;
  } else
    ans += zero;
  cout << ans << endl;
}
