#include<bits/stdc++.h> using namespace std; int main(){ int h[105]; int n; double ave=0; cin>>n; for (int i=1; i<=n; i++){ cin>>h[i]; ave += h[i]; } ave /= n; printf("%.1f\n",ave); for (int i=1,first=0; i<=n; i++) if (h[i]>ave){ if (++first>1) cout<<" "; cout<<i<<":"<<h[i]; } cout<<endl; return 0; }