using System;
using System.Collections.Generic;

public static class Kata
{
  public static bool IsPangram(string str)
  {    
    List<string> filteredStrList = new List<string>();
    string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int containedLetterNum = 0;
    
    foreach(char ch in str.ToLower())
    {
      if(Char.IsLetter(ch))
      {
        filteredStrList.Add(ch.ToString());
      }
    }

    string filteredString = string.Join("", filteredStrList.ToArray());

    foreach(char ch in alphabet.ToLower())
    {
      if(filteredString.Contains(ch))
      {
        containedLetterNum++;
      }
    }
    
    if(alphabet.Length - containedLetterNum <= 0)
    {
      return true;
    }
    else
    {
      return false;
    }
  }
}