#include<iostream>
#include<iomanip>
#include<vector>
using namespace std;
class rain()
{
    public:
    static double total;
    public:
    static void 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;
}