def counts(nums: list[int]) -> dict[int, int]:
    ret = {}
    for n in nums:
        if n in ret:
            ret[n] += 1
        else:
            ret[n] = 1
    return ret


if __name__ == '__main__':
    with open('1.input') as file:
        left, right = [], []
        for line in file:
            l, r = line.split()
            l, r = int(l), int(r)
            left.append(l)
            right.append(r)
    # how many times does each number apear in each list
    right = counts(right)
    score = sum([0 if n in right else n * right[n]  for n in left])
    for n in left:
        if n not in right: continue
        score += n * right[n]
    print(score)