#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5;
int N, A[MAXN + 10], cnt, cnt2;
long long ans;
int main() {
  int i, j;
  scanf("%d", &N);
  for (i = 1; i <= N; i++) scanf("%d", &A[i]);
  for (i = 1; i <= N; i++) {
    if (A[i] <= -1) ans += -1 - A[i], cnt++;
    if (A[i] >= 1) ans += A[i] - 1;
    if (A[i] == 0) ans++, cnt2++;
  }
  if (cnt % 2) {
    if (cnt2 == 0) ans += 2;
  }
  printf("%lld", ans);
}
