using System.Collections.Generic;
public static void Main()
StringBuilder sb = new StringBuilder();
List<string> sbV= new List<string>();
List<string> vowels = new List<string>();
if(vowels.Contains(s[i].ToString()))
sbV.Add(s[i].ToString());
Stack<char> Vstack = new Stack<char>();
if(vowels.Contains(g.ToString()))
StringBuilder sbStack = new StringBuilder();
if(vowels.Contains(g.ToString()))
sbStack.Append(Vstack.Pop());
Console.WriteLine("sbStack:"+sbStack);
for(var k=0 ; k<s.Length ;k++)
if(vowels.Contains(s[k].ToString()))
sb[k]=Convert.ToChar(sbV[q]);