#include<iostream>
using namespace std;
class Rainfall()
{
    public:
    static double total;
    static bool addRainfall(double value)
    {
        if(value<0)
        {
            cout<<"Invalid Rainfall";
            return false;
        }
        total +=value;
        return true;
    }
};
double Rainfall::total=0;
int main()
{
    int n;
    if(!(cin>>n))
    {
        cout<<"Incomplete Data";
        return 0;
    }
    for(int i=0;i<n;i++)
    {
      double rain;
      if(!(cin>>rain))
      {
          cout<<"Incomplete Data";
          return 0;
      }
      if(!Rainfall::addRainfall(rain))
      {
          return 0;
      }
    }
    cout<<fixed<<setprecision(2)<<Rainfall::total;
    return 0;
}