#include <iostream>
#include <cstdlib>
using namespace std;
int main(){
    int n;
    if(!(cin>>n)) return 0;
    for(int i=0; i<n; ++i){
        int production;
        cin>>production;
        if(production<0){
            cout<<"Invalid Production"<<endl;
            exit(0);
        }
        totalProduction += production;
    }
    cout<<totalProduction<<endl;
    return 0;
}