text: str

with open("test.txt") as f:
    text = f.read()

lines: list[str] = text.splitlines()
data: list[list[str]] = [line.split("   ") for line in lines]

right_data: list[str] = [tmp[1] for tmp in data]
left_data: list[str] = [tmp[0] for tmp in data]

right: list[int] = list(map(int, right_data))
left: list[int] = list(map(int, left_data))

right.sort()
left.sort()

print(sum(map(abs, [x * right.count(x) for x in left])))