C# please, thank you! Will upvote.

Problem 1 (30 points): Ask the user to enter a string (e.g. "Welcome to Saint Martin's U!"). Your program should count and display to the console the total number of vowels (A, E, I, O, U) - count both uppercase and lowercase vowels - in that given input. In the example above, the output should 9. Problem 2 (30 points): Ask the user to enter a positive integer b. Validate the input (to make sure it is positive). Then output whether or not the number b is divisible by 3. Problem 3 (40 points): given a file input.txt (create your own input.txt file!) count and display to the console the total number of vowels (A, E, I, O, U) in it