first time offense on a class a felony..possession of a controlled substance in a public park under 28 grams

I don't have my code in front of me, but I'm pretty sure that's a PCS 4-28 grams case. Without any enhancements, I believe the range of punishment there is for a 2nd degree felony. The potential range of punishment for a 2nd degree felony is up to 20 years in prison (2-20; $10,000 fine). You definitely need to consult with and hire an experienced defense attorney to represent you. In those cases, a lot of the time there are issues with the way in which the cops seized the drugs. If there are those kind of issues, your lawyer may be able to exploit them to your advantage.