Whilst the service runs a premier train (which alludes to semi-luxury and costs a lot more than our sleeper compartments),
the economy sleeper train wasn't doing so well, so they reduced the number of sleeper compartments (each has six 4 - person compartments and two 2 - person coupés) and, it seems, added them to the sitter «economy» trains; nine sitter compartments — each of which take 18 rows of 4 seats (I'll leave you to do the maths) and called it a tourist train.