The conductor's office seat of k5 16 train happens to be in car 15, and the number of people is 1 12, so your number 83 is the window. See the figure below.

Car 1 to 12 is a hard sleeper, 13 is a soft sleeper, 14 is a dining car, 15 is a hard-seat car with a conductor's office seat, and 16 to 19 is the number of seats.