#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vd = vector<double>;
int main() {
  int n;
  cin >> n;
  vd v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  double ans = v[0];
  for (int i = 1; i < n; i++) {
    ans = (ans + v[i]) / 2;
    cout << ans << "," << v[i] << endl;
  }
  cout << ans << endl;
}
