#include <bits/stdc++.h>
using std::fabs;
const int maxn = 1e5 + 5;
int n;
long long dp[maxn][2];
long long val[maxn];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%I64d", &val[i]);
  dp[1][0] = fabs(val[1] + 1);
  dp[1][1] = fabs(val[1] - 1);
  for (int i = 2; i <= n; i++) {
    dp[i][0] = std::min(dp[i - 1][0] + fabs(val[i] - 1),
                        dp[i - 1][1] + fabs(val[i] + 1));
    dp[i][1] = std::min(dp[i - 1][0] + fabs(val[i] + 1),
                        dp[i - 1][1] + fabs(val[i] - 1));
  }
  printf("%I64d", dp[n][1]);
  return 0;
}
