PrSet4

#include <fstream>
#include <algorithm>
#include <set>
#include <vector>
#include <iostream>
using namespace std;

int main()
{
    ifstream in("input.txt");

    int n;
    in >> n;
    set<int> s;
    set<int> plus;
    set<int> minus;
    set<int>::iterator i;

    int t;
    for (int it = 0; it < n; it++)
    {
        in >> t;
        s.insert(t);
    }
    cout << "s:";
    for (i = s.begin(); i != s.end(); i++)
        cout << *i << " ";
    cout << endl << "plus:";
    int a,b;
    for (i = s.begin(); i != s.end(); i++)
    {
        a = *i;
        if (a > 0)
            while (a % 10 != 0)
            {
                b = a % 10;
                a = a / 10;
                plus.insert(b);
            }
        else
            while (a % 10 != 0)
            {
                b = (a % 10)*(-1);
                a = a / 10;
                minus.insert(b);
            }
    }

        for (i = plus.begin(); i != plus.end(); i++)
        cout << *i << " ";
        cout << endl << "minus:";

        for (i = minus.begin(); i != minus.end(); i++)
        cout << *i << " ";
        cout << endl << "result:";

    s.clear();
    set_difference(minus.begin(), minus.end(), plus.begin(), plus.end(),
    std::inserter(s, s.end()));

    for (i = s.begin(); i != s.end(); i++)
        cout << *i << " ";
    return 0;
}