# Time to make a function that modifies its own behaviour after the first time
# it's called with specific arguments!

needs_input = True
def canvas_read(x, y):
    global needs_input
    # Only ask for input the first time x>=0, y=-1 is read
    if needs_input and y == -1 and x >= 0:
        get_input()
        needs_input = False

    if (x, y) not in canvas:
        canvas[(x,y)] = (0, 0)
    return canvas[(x,y)]

# Hmm... Global variables are gross. Let's try that again.

def canvas_read(x, y, IGNORE_ME=[1]):
    # Only ask for input the first time x>=0, y=-1 is read
    if IGNORE_ME[-1] and y == -1 and x >= 0:
        get_input()
        IGNORE_ME.append(0)

    if (x, y) not in canvas:
        canvas[(x,y)] = (0, 0)
    return canvas[(x,y)]

# Abusing mutable default argument behaviour? If Python ever changes it to be
# less silly, this will be hard to port to Python 3. One more try.

def canvas_read(x, y):
    # Only ask for input the first time x>=0, y=-1 is read
    if y == -1 and x >= 0:
        get_input()

        def no_input_check(x,y):
            if (x, y) not in canvas:
                canvas[(x,y)] = (0, 0)
            return canvas[(x,y)]

        canvas_read.__code__ = no_input_check.__code__

    if (x, y) not in canvas:
        canvas[(x,y)] = (0, 0)
    return canvas[(x,y)]

# This is the most beautiful code I've ever written.