#include <fstream>
#include <iterator>
#include <algorithm>
#include <set>

using namespace std;


int main() {
    setlocale(LC_ALL, "Russian");

    fstream fst("file_name.txt");
    istream_iterator<int> fst_it(fst);
    istream_iterator<int> end_of_file;
    multiset<int> s(fst_it, end_of_file);
    fst.close();

    fst.open("file_name.txt");
    ostream_iterator<int> ost(fst, " ");
    copy(begin(s), end(s), ost);

    return 0;
}