Two arrays of integers `a` and `b` are given, both sorted in non-decreasing order (they may have repeated values within each array). Print the values that appear in both arrays, each common value printed exactly once, in non-decreasing order. The required algorithm is a variant of the two-pointer merge: when `a[i] < b[j]` advance `i`, when `a[i] > b[j]` advance `j`, and on equality add the value to the result and advance both indices. Input: The program reads from standard input: - a natural number `n`, followed by `n` integers (array `a`); - a natural number `m`, followed by `m` integers (array `b`). - `1 <= n, m <= 1000` - `-1000000 <= values <= 1000000` - the arrays are sorted in non-decreasing order and may contain duplicates Output: The program prints on the first line the number `k` of distinct values common to both arrays. If `k > 0`, the second line contains the `k` values, separated by a single space. If `k = 0`, no further line is printed. Example: Input: 5 1 2 3 4 5 4 2 4 6 8 Output: 2 2 4