#include <algorithm>
#include <iostream>
#include <iterator>
#include <regex>
#include <string>
#include <vector>
 
using namespace std;
 
int main() {
    const auto s1 = "The ,qu\\,ick ,\tbrown, fox"s;
    const auto s2 = "The quick brown fox"s;

    const regex re{ "([^ ,.!?;:]+)" };
    vector<string> s1Tokens{ sregex_token_iterator(cbegin(s1), cend(s1), re, 1), sregex_token_iterator() };
    vector<string> s2Tokens{ sregex_token_iterator(cbegin(s2), cend(s2), re, 1), sregex_token_iterator() };
 
    sort(begin(s1Tokens), end(s1Tokens));
    sort(begin(s2Tokens), end(s2Tokens));
 
    set_difference(cbegin(s1Tokens), cend(s1Tokens), cbegin(s2Tokens), cend(s2Tokens), ostream_iterator<string>(cout, "\n"));
}