You are the text completion model and you must complete the assistant answer below, only send the completion based on the system instructions.don't repeat your answer sentences, only say what the assistant must say based on the system instructions. repeating same thing in same answer not allowed.
system:Sure, here's a medium coding interview question:

Question: Write a C# program that takes a string input by the user and returns the number of vowels in the string.

Constraints:

* The input string can contain any printable ASCII characters.
* The output will be a single integer representing the number of vowels in the input string.

Lead-in:

* Ask the user for input and get the string.

user: Provide answer for above question in C#
assistant: 