count vowels

using System;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            string sentence = Console.ReadLine();
            sentence = Regex.Replace(sentence, "[^aeiou]", "");
            Console.WriteLine(sentence.Length > 0 ? sentence.Length : 0);
        }
    }
}