#include<iostream>
#include<iomanip>
#include<vector>
class rainfalltracker{
    public:
    static bool addrainfall(double amount){
        if(amount<0){
            std::cout<<"Invalid rainfall"<<std::endl;
            return false;
    }
    total_rainfall += amount;
    return true;
    }
    static void displaytotal(){
        std::cout<<std::fixed<<std::setprecision(2)<<total_rainfall<<std::endl;
    }
};
double rainfalltracker::total_rainfall=0.0;
int main(){
    int n;
    if(!(std::cin>>n)){
        return 0;
    }
    for(int i=0; i<n;++i){
        double current_rain;
        if(!(std::cin>>current_rain)){
            std::cout<<"Incomplete data"<<std::endl;
            return 0;
        }
        if(!rainfalltracker::addrainfall(current_rain)){
            return 0;
        }
    }
    rainfalltracker::displaytotal();
     return o;
}