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