#include <bits/stdc++.h>
int main() {
  long long int n, a[1000000], i, s = 0, neg = 0, zero = 0;
  scanf("%lld", &n);
  for (i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
    if (a[i] < 0) {
      neg++;
      s = s - a[i] - 1;
    } else if (a[i] > 0) {
      s = s + a[i] - 1;
    } else
      zero++;
  }
  if (zero > 0)
    s = s + zero;
  else {
    if (neg % 2 != 0) s = s + 2;
  }
  printf("%lld\n", s);
  s = 0;
  zero = 0;
  neg = 0;
  return 0;
}
