#include <iostream>
#include <regex>
using namespace std;
 
int main() {
	std::vector<std::string> strings;
	strings.push_back("<firstname>Anna</firstname>");
	strings.push_back("<firstname>Anna Lena</firstname>");
	std::regex reg("(<firstname>)([a-zA-Z0-9\\s]*)(</firstname>)");
	for (size_t k = 0; k < strings.size(); k++)
	{
		smatch s;
		if (std::regex_match(strings[k], s, reg)) {
			strings[k] = s[2];
			std::cout << strings[k] << std::endl;
		}
	}
	return 0;
}

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