public class Robot {
    public static final int HALLWAY_LENGTH = 10;
    public static final int NORTH = 1;
    public static final int SOUTH = -NORTH;
    
    private int dir = NORTH, pos = 1;
    
    public void step() {
	if (wallInFront())
	    System.err.println("Ouch, I bumped my head!");
	else
	    pos += dir;
    }
    
    public void step(int n) {
	while (n != 0) { 
	    step();
	    n--;
	}
    }

    public boolean wallInFront() {
	return false;
    }
    
    public void turnAround() {
	dir = -dir;
    }
    
    public String toString() {
	String orientation = "north";
	if (dir == SOUTH)
	    orientation = "south";
	return "I am at position " +
	    pos + " facing " + orientation + ".";
    }
}