#include <bits/stdc++.h>
using namespace std;
long long a[100010];
int main() {
  long long n;
  scanf("%I64d", &n);
  long long sum1 = 0, sum2 = 0, ans = 0, sum0 = 0;
  for (long long i = 0; i < n; i++) {
    scanf("%I64d", &a[i]);
    if (a[i] == 0) {
      sum0++;
      continue;
    } else if (a[i] < 0) {
      ans += -1 - a[i];
      sum1++;
    } else {
      ans += a[i] - 1;
      sum2++;
    }
  }
  if (sum0 == 0) {
    if (sum1 % 2 == 0) {
      printf("%I64d", ans);
    } else {
      printf("%I64d", ans + 2);
    }
  } else {
    printf("%I64d", ans + sum0);
  }
}
