public static bool IsPangram(string input)
{
HashSet <char> uniqueLetters = new HashSet <char>();
foreach (char c in input.ToLower())
{
if (Pangram.IsAlpha(c))
{
uniqueLetters.Add(c);
}
}
if (uniqueLetters.Count == 26)
{
return(true);
}
return(false);
}