Symmetric difference of two sorted arrays

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Problem

Two sequences of integers `a` and `b` are given, both sorted in ascending order. Print the values that appear in exactly one of the two sequences (in `a` but not in `b`, or in `b` but not in `a`), each value appearing once, in ascending order. This result is called the symmetric difference `A xor B`. The required solution is a single pass with two indices, in merge style: when the two current values differ, the smaller one enters the result; when they are equal, both values cancel each other and you skip all occurrences of them.

Input format

Input input.txt

The program reads from standard input: - a natural number `n`, followed by `n` integers (sequence `a`); - a natural number `m`, followed by `m` integers (sequence `b`). - `1 <= n, m <= 1000` - `-1000000 <= values <= 1000000` - the sequences are sorted in ascending order and may contain duplicates

Output format

Output output.txt

The program prints on the first line the number `k` of distinct values in the symmetric difference. If `k > 0`, the second line contains the `k` values in ascending order, separated by single spaces. If `k = 0`, no further line is printed.

Example

input

output

5

1 3 5 6 8

Sample cases (from the problem)

Sample Case 1

Input

Expected output

5

1 3 5 6 8

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