// editor1
#include<iostream>
using namespace std;
class A{
    public:
    static void total (int arr[],int n){
        int sum=0;
        for(int i=0;i<n;i++){
            if(arr[i]<0){
                cout<<"Invalid Production"<<endl;
                continue;
            }
            sum+=arr[i];
    }
    cout<<sum<<endl;
}
}
int main(){
    int n;
    cin >>n;
    int arr[n];
    for(int i=0;i<n;i++){
        cin>>arr[i];
    }
    A::total(arr,n);
    return 0;
}