#include<iostream>
using namespace std;
void production(int items)
{
    static int total=0;
    if(items<0)
    {
        cout<<"Invalid Production";
        exit(0;)
    }
    total+=total;
}

int main()
{
int n;
cin>>n;
int value;
static int total=0;
for(int i=0;i<n;i++)
{
    cin>>value;
    if(value<0)
    {
        cout<<"Invalid Production";
        return 0;
    }
    total==value;
}
cout<<total;
return 0;
}