// editor1
#include<iostream>
using namespace std;
class Machine
{
    int itemProduced;
    static int totalProduction;
    public:
    void recordProduction(int item)
    {
        if(item<0)
        {
            cout<<"Invalid Production"<<endl;
        }
        else
        {
            itemProduction =items;
            totalProduction +=items;
        }}
        static int getTotalProduction()
        {
            return totalProduction;
        }};
        int Machine::totalProduction=0;
        int main()
        {
            int n;
            cin>>n;
            Machine m;
            for(int i=0;i<n;i++)
            {
                int items;
                cin>>items;
                m.recordProduction(items);
            }
            cout<<Machine::getTotalProduction()<<endl;
            return 0;
            }
        }
        }
        }
    }
}