#include<iostream>
using namespace std;
class Production
{
    private:
    static int total;
    public:
    static void calculate()
    {
        int n;
        cin>>n;
        total =0;
        for(int i=0;i<n;i==)
        {
            int items;
            cin>>items;
            if(items<0)
            {
                cout<<"Invalid Production;
                return;
            }
            total==items;
        }
        cout<<total;
    }
    
};
int Production::total=0;
int main()
{
    Production::calculate();
    return 0;
}