#include <bits/stdc++.h>
int main() {
  long long int a, b, count2 = 0, c, d, e, i, j, n, x, y, count = 0, sum = 0;
  scanf("%lld", &n);
  for (i = 0; i < n; i++) {
    scanf("%lld", &a);
    if (a < 0) {
      count++;
    }
    if (a == 0) {
      count2++;
    }
    if (a <= 0) {
      sum = sum + (1 - a);
    } else {
      sum = sum + (a - 1);
    }
  }
  c = count / 2;
  d = sum - (c * 2 * 2);
  e = count % 2;
  if ((e > 0) && (count2 > 0)) {
    d = d - 2;
  }
  printf("%lld", d);
}
