#include <iostream>
using namespace std;
class Factory{
private:
    static int totalProduction;
public:
     static void addproduction(int iteams){
         if(iteams <0){
            cout<<"Ivalid production";
            exit(0);
         }
         totalProduction+=iteams ;
         
     }
     static int getTotalProduction(){
         return totalProduction;
     }
};
int Factory::totalProduction =0;
int main(){
    int n;
    cin>>n;
    for (int i=0;i<n;i++){
        int items;
        cin >>items;
        Factory::addProduction(items);
    }
    cout<<Factory::getTotalproduction();
    return 0;
}