#include<iostream>
using namespace std;
void add(int x)
{
    static int sum = 0;
    if(x<0)
    {
        cout<<"Invalid Production";
        exit(0);
    }
    sum+=x;
    cout.flush();
    if(cin.peak()==EOF)cout<<sum;
}
int main()
{
    int n,x;
    cin>>n;
    while(n--)
    {
        cin>>x;
        add(x);
    }
}