#include<bits/stdc++.h> using namespace std; double b,a[101],ans; int main(){ cin>>b; for(int i=1;i<=b;i++){ cin>>a[i]; ans+=a[i]; } ans/=b; printf("%.1lf",ans); cout<<endl; for(int i=1;i<=b;i++){ if(ans<a[i]){ cout<<i; cout<<":"; cout<<a[i]; cout<<" "; } } return 0; }