This is the 16973rd most frequent Russian word.
составу
"Sоставу" is the dative case of "состав," meaning "composition" or "structure."
The word 'составу' in this context refers to the qualities or characteristics of a train's composition (train cars).
Этот поезд отличается повышенной комфортностью состава.
This train is characterized by the enhanced comfort of its composition.
Here, 'составу' denotes the makeup or organization of a team.
Мы уделяем внимание составу нашей команды.
We pay attention to the composition of our team.
In this sentence, 'составу' refers to the contents or ingredients of medicines.