Input data contain restriction :
'(1 ≤ n ≤ 1000000000)'

But output examples contain :

int n = 7230702951;
Line.WhoIsNext(names, n) --> "Leonard"

7230702951 is more than 1000000000

this example is not correct according to input restrictions. Please fix

In expected results listed :
int n = 7230702951;
Line.WhoIsNext(names, n) --> "Leonard"

but in Input value n must be not bigger than 1000000000
obviously 7230702951 more than 1000000000 something have to fixed...

Tests 18,19 and 20 returned : System.ArgumentNullException : Value cannot be null. Parameter name: destinationArray. They all run less than 2 sec. What does it mean? I do not use variable named destinationArray. Sorry I'm new here. Thanks.