Olimpiadi Liste

#include <iostream>
#include <fstream>
#include <list>
#include <algorithm>
#include <iterator>

using namespace std;

int rec(list<int> A, int N) {
    for(list<int>::iterator r = A.begin(); r != A.end(); ++r)
        cout << *r <<" ";

    cout <<"\n";

    if (N > 1) {
        list <int>::iterator i2 = A.begin();
        for (list <int>::iterator i = A.begin(); i != A.end();i++) {

            i2++;
            int sum = *i + *(i2);

            //cout <<"    " << sum << "\n";
            if (sum % 2 != 0)
            {

                list <int> b;
                for(list <int>::iterator k = A.begin();k!=i;k++)
                    b.push_back(*k);


                for(list <int>::iterator k = ++i2;k!=A.end();k++)
                    b.push_back(*k);

                i2--;
                return rec(b, N - 2);
            }

        }

    }
    return *A.begin();
}



int main(int argc, char** argv) {
    ifstream in("input.txt");
    ofstream out("output.txt");
    int n;
    in >> n;
    int d;
    list<int> a;
    for (int i = 0; i < n; i++) {
        in >> d;
        a.push_back(d);
    }


    out << rec(a, n);

    return 0;
}