#include<iostream>
using namespace std;
int main()
{
    int n;
    cin>>n;
    try
    {
        if(n<-10 || n>12)
        {
            throw "Invalid input";
        }
    int val[n];
    int ans=0;
    for(int i=0;i<n;i++)
    {
     cin>>val[i];
     if(val[i]<0)
     {
         throw "Invalid input";
     }
     ans+=val[i];
    }
}
cout<<ans;
catch(const char* msg)
{
   cout<<msg; 
}
return 0;
}