Do not exchange money on the train

One member of our hike on Carpathians, on the road from St. Petersburg in Ivano-Frankivsk to exchange money on the train and became a happy owner of counterfeit 500-hryvnia banknotes (about 2000 rubles). Do not change money (rubles on the hryvnia) in trains! Course there is certainly tempting, but you almost certainly "pop in" a couple of counterfeit notes (if not all).

At each station there are several official exchange offices (with a bad rate, but with real money). Not worth risking for the sake of hundreds of thousands.