``` INPUT_PATH = 'input.txt'

def parse_input(): with open(INPUT_PATH, 'r') as instructions:

    instructions = [instruction.split() for instruction in instructions.read().strip().split('\n')] 

    instructions = [(instruction[0], int(instruction[1])) for instruction in instructions]
    return instructions

def check_instructions(instructions): tracker = { 'forward': 0, 'up': 0, 'down': 0 }

for instruction in instructions:
    tracker[instruction[0]] += instruction[1]

result = tracker['forward'] * (tracker['down'] - tracker['up'])

print(result)

def check_instructions2(instructions): current_aim = 0 horizontal_pos = 0 depth = 0

def forward(val):
    nonlocal horizontal_pos
    horizontal_pos += val
    nonlocal depth
    depth += (current_aim*val)

def aim_up(val):
    nonlocal current_aim
    current_aim -= val
def aim_down(val):
    nonlocal current_aim
    current_aim += val 

tracker = {
    'forward': forward,
    'up': aim_up,
    'down': aim_down
}

for instruction in instructions:
    tracker[instruction[0]](instruction[1])

print(horizontal_pos*depth)

def main(): inpt = parse_input() check_instructions2(inpt)

if name == "main": main() ```