практика_сеты2_6

#include <vector>
#include <string>
#include <iterator>

using namespace std;

int main()
{
    set <char> s1;
    set <char> s2;
    set <char> s3;
    string tmp;
    ifstream in("input.txt");
    ofstream out("output.txt");
    string temp;
    getline(in, temp);
    for (unsigned int i = 0; i < temp.size(); i++)
        if (ispunct(temp[i]))
            s2.insert(temp[i]);
    while (getline(in, tmp))
    {
        for (unsigned int i = 0; i < tmp.size(); i++)
            if (ispunct(tmp[i]))
                s1.insert(tmp[i]);
        set_intersection(s1.begin(), s1.end(), s2.begin(), s2.end(), inserter(s3, s3.begin()));
        s2 = s3;
        s3.clear();
        s1.clear();
    }
    if (s2.empty()) out << "There are no the same sign!";
    for (set <char>::iterator iter = s2.begin(); iter != s2.end(); iter++)
        out << *iter << " ";
    return 0;
}