#include<iostream>
using namespace std;
class Factory{
    public:
    static int total;
    static bool add(int x){
        if(x<0){
            cout<<"Invalid Production";
            return false;
        }total+=x;
        return true;}
    };
    int Factory::total=0;
    int main(){
        int n,x;
        cin>>n;
        for(int i=0;i<n;i++){
            cin>>x;
            if(!Factory::add(x))
            return 0;
        }
    }cout<<Factory::total;
    return 0;
}