public boolean checkUsername(String username)
	{
		if(username.isEmpty())
			return false;
		for(char c : username.toLowerCase().toCharArray())
		{
			int tmp = c;
			if(!(tmp > 96 && tmp < 123) || tmp==230 || tmp==248 || tmp==229) // Checking username letters
				return false;
		}
		return true;
	}