#include <bits/stdc++.h>
using namespace std;
const int maxn = 100000 + 10;
int a[maxn], b[maxn];
int main() {
  int n;
  scanf("%d", &n);
  long long ans = 0;
  int cnt1 = 0, cnt2 = 0, cnt0 = 0;
  for (int i = 1; i <= n; i++) {
    scanf("%d", a + i);
    if (a[i] <= -1) {
      ans += -1 - a[i];
      cnt1++;
    } else if (a[i] >= 1) {
      ans += a[i] - 1;
      cnt2++;
    } else {
      cnt0++;
    }
  }
  if (cnt1 % 2) {
    if (cnt0) {
      ans += cnt0;
    } else {
      ans += 2;
    }
  } else {
    ans += cnt0;
  }
  printf("%lld\n", ans);
  getchar();
  getchar();
  return 0;
}
