// editor2
#include <iostream>
#include <iomanip>
using namespace std;
class rainfall{
    public:
    float count;
    int days;
    static float result=0;
    
    void calc(int days){
        for (int i=0;i<=days;i++){
            cin>>count;
            if (count<0){
                cout<<"Invalid Rainfall";
            }
            result+=count;
        }
        cout<<fixed<<setprecision(2)<<result;
    }
};


int main(){
 rainfall    rain ;
    int day;
    cin>>day;
    rain.calc(day);
    return 0;
}