#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 100;
int n, a[maxn], b[maxn];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  int cnt = 0;
  for (int i = 1; i <= n; i++) {
    int tmp1 = abs(1 - a[i]);
    int tmp2 = abs(-1 - a[i]);
    if (tmp1 > tmp2) {
      b[i] = tmp2;
      cnt++;
    } else {
      b[i] = tmp1;
    }
  }
  if (cnt % 2 == 0) {
    long long sum = 0;
    for (int i = 1; i <= n; i++) {
      sum += b[i];
    }
    printf("%lld\n", sum);
  } else {
    int flag = 0;
    for (int i = 1; i <= n; i++) {
      if (a[i] == 0) {
        flag = 1;
        break;
      }
    }
    long long sum = 0;
    for (int i = 1; i <= n; i++) sum += b[i];
    if (flag)
      printf("%lld\n", sum);
    else
      printf("%lld\n", sum + 2ll);
  }
  return 0;
}
