string[] names = new string[] { "Sheldon", "Leonard", "Penny", "Rajesh", "Howard" };
Line.WhoIsNext(names, 1) == "Sheldon"
Line.WhoIsNext(names, 52) == "Penny"
Line.WhoIsNext(names, 7230702951) == "Leonard"

this is some conditions of the task.

and when I try to solve this task in my IDE, 7 230 702 951 - "the number is too large for int"

In descritption we see:
"The input data consist of an array which contains five names, and single integer n.
(1 ≤ n ≤ 1 000 000 000)."
But in output/examples we must receive "Leonard" for n == 7 230 702 951.
How can it be possible? It is more than int.