C++11 provides support for regular expressions within the standard library in the header
regex through a set of classes, iterators, and algorithms. Regular expressions are used to perform pattern matching within strings.
The following example checks if an input string represents a valid email address.
The example above verified a string by checking for a regex match.
However the regex library allows also to search for matches and replace certain patterns.
Try to solve the next exercise by using the right classes and algorithms from