Little Elephant and CNSes

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A Little Elephant from the Zoo of Lviv likes lucky strings, i.e., the strings that consist only of the lucky digits 4 and 7. The Little Elephant has N favorite strings S1, S2, ..., SN and the favorite number K. Each character in Si (1 ≤ i ≤ N) is either the lucky digit (4 or 7) or the question mark ?. Consider some non-decreasing lucky string S. In other words, S has one of the following forms:

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solution.cppC++17

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