#include<iostream>
using namespace std;
int main(){
int n;
cin>>n;
 try{
     if(n<1||n>10){
         throw "Invalid input";
     }
     double grade, sum=0;
     for(int i=0;i<n;i++){
         cin>>grade:
         if(grade<0){
             throw "Invalid input";
         }
         sum+=grade;
     }
     double gpa=sum/n;
     cout<<gpa;
 }
 catch(const char*a){
     cout<<a;
 }
 return 0;
 }