#include<iostream>
#include<iomanip>
#include<vector>
using namespace std;
class rain{
    private:
    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)){
        return 0;
    }
    double curentrain;
    for(int i=0;i<n;++i){
        if(!(cin>>curentrain)){
            cout<<"Incomplete data";<<endl;
            return 0;
        }
        if(curentrain<0){
            cout<<"Invalid rainfall"<<endl;
            return 0;
        }
        rain::addrain(curentrain);
        
    }
    cout<<fix<<setprecision(2)<<rain::gettotal()<<endl;
    return 0;
}