#include<iostream>
#include<iomanip>
#include<vector>
using namespace std;
class rain
{
    public:
    static double total;
    public:
    static bool addrain(double amount)
    {
        total+=amount;
    }
    static double gettotal()
    {
        return total;
    }
};
double rain::total = 0.0;
int main()
{
    int n;
    if (!(cin>>n))
    {
        //cout<<"Incomplete Data";
        return 0;
    }
    double curentrain;
    for (int i = 0; i<n; i++)
    {
        if(!(cin>>curentrain))
        {
            cout<<"Incomplete Data";
            return 0;
        }
        if(curentrain<0)
        {
            cout<<"Invalid Rainfall"<<endl;
            return 0;
        }
        rain::addrain(curentrain);
    }
    cout<<fixed<<setprecision(2)rain::gettotal()<<endl;
    return 0;
}
}