Find correct arithmetic expressions

Cost: $8|$ Solved: $5$

Memory limit: $256$ Mb

Time limit: $1000$ ms

Input file: stdin

Output file: stdout

Task:

You are given a set of strings separated with line feed characters.

We'll be considering a string a correct arithmetic expression if it consists of positive integers separated with math symbols $+,-,**\frac{,}{?}$ without whitespace character in between. A single

digit is also considered to be a correct arithmetic expression.

Find all the longest substrings containing correct arithmetic expressions.

Input:

A set of strings separated with line feed characters.

Output:

All the longest correct substrings in the order in which they appear in the text, separating each with a line feed character.

$**$ Use only C$++**$