#include<iostream>
#include <list>
using namespace std;

int main(void) {
       list<int> l{1,2,3,4,5};
       l.push_back(6);
       l.push_front(8);
      list<int>::iterator p;
      for (p=l.begin(); p!=l.end();p++) {
          cout <<*p <<" ";
      }
       int sum=0;
       while (!l.empty()) {
             sum+=l.front();
             l.pop_front();
       }
       cout <<"sum=" <<sum <<endl;
      
       return 0;
}