function DayOfWeek(Letter: Char): String;
var
  DayOfTheWeek_Short, DayOfTheWeek_Long: array of String;
  I: Integer;
begin
  SetLength(DayOfTheWeek_Short, 7);
  SetLength(DayOfTheWeek_Long, 7);

  DayOfTheWeek_Short := ['s', 'm', 't', 'w', 't', 'f', 'a'];
  DayOfTheWeek_Long := ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday',
    'Friday', 'Saturday'];

  for I := 0 to 6 do
  begin
    if(Lowercase(DayOfTheWeek_Short) = Lowercase(DayOfTheWeek_Long)) then
    begin
      Result := DayOfTheWeek_Long[I];
      Exit;
    end;
  end;

  Result := 'NONE';
end;