Lost rare 1970s comic book with bright red Batman cover near a coffee shop downtown Sioux Falls.

I was at a coffee shop near downtown Sioux Falls about a week ago when I realized my prized possession, a rare comic book from the 1970s, had slipped from my bag. It's got a bright red cover with Batman on the front, and I've carried it with me for years. I checked all around the shop and retraced my steps, but no luck. I'm really hoping someone finds it and returns it to me!