using System;

public class Program

{

     static bool isVowel(char letter)

    {

        if(letter == 'a' ||

           letter == 'e' ||

           letter == 'i' ||

           letter == 'o' ||

           letter == 'u') return true;

        return false;

    }

    public static void Main()

    {

        Console.Write("Input string: ");

        string word = Console.ReadLine();

        int vowelCounter = 0;

        for(int i=0; i<word.Length; i++) 

        {

            if(isVowel(word[i])) vowelCounter++;        

        }

        Console.WriteLine("Number of vowels: " + vowelCounter);

    }

}