#include<iostream>
using namespace std;
 
 class Factory {
     public:
     static int totalProduction
 };
 int Factory::totalProduction =0;
 
 int main()
 {
     int n;
     cin >> n;
     fir (int i =0; i < n; i++)
     {
         int iteam;
         cin >> iteam;
         if(iteam < 0)
         cout << "Invalid Production" << endl;]
         else
              Factory::totalProduction+=iteam;
     }
     cout << Factory::totalProduction << endl;
     return 0;
 }