#include<iostream 
using namespace std;

int main(){
    int n;
    cin>>n;
    
    try{
        if(n<1||n>10){
            throw "Invalid input";
        }
        double grade;
        double sum=0;
        
        for (int i=0;i<n;i++){
            
            if (grade<0){
                throw "Invalid input";
            }
            sum+=grade;
        }
        double gpa=sum/n;
        cout<<gpa;
    }
    catch (const char*msg){
        cout<<msg;
    }
    return 0;
}