#include<iostream>
using namespace std;
class Machine{
private:
     int itemsProduced;
     static int totalProduction;
public:
     void recordProduction(int items){
         if (items<0){
             cout<<"Invalid Production"<<endl;
         }else{
             itemsProduced=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;
}