private String getInput(){
		@SuppressWarnings("resource")
		Scanner scanner = new Scanner(System.in);
		String userInput;
		do{
			System.out.print("Enter your move [WASD?]: ");
			userInput = scanner.nextLine();
			userInput = userInput.trim().substring(0, 1);
			if(VALID_KEYS.contains(userInput.toUpperCase())){
				continue;
			}
			else if(userInput.equals("?")){
				printHelp();
			}
			else{
				System.out.println("Invalid move. Please enter just A (left), S (down), D (right), or W (up).");
			}
		}while(!VALID_KEYS.contains(userInput.toUpperCase()) || userInput.isEmpty());
		return userInput;
	}