      
    HAI  
    I HAS A TUX  
    GIMMEH TUX  
    I HAS A FOO ITS 0  
    I HAS A BAR ITS 0  
    I HAS A BAZ ITS 0  
    I HAS A QUZ ITS 1  
    TUX IS NOW A NUMBR  
    IM IN YR LOOP NERFIN YR TUX TIL BOTH SAEM TUX AN 0  
    I HAS A PUR  
    GIMMEH PUR  
    PUR IS NOW A NUMBR  
    FOO R SUM OF FOO AN PUR  
    BAR R SUM OF BAR AN 1  
    BOTH SAEM BIGGR OF PRODUKT OF FOO AN QUZ AN PRODUKT OF BAR BAZ AN PRODUKT OF FOO AN QUZ  
    O RLY?  
    YA RLY  
    BAZ R FOO  
    QUZ R BAR  
    OIC  
    IM OUTTA YR LOOP  
    BAZ IS NOW A NUMBAR  
    VISIBLE SMOOSH QUOSHUNT OF BAZ QUZ  
    KTHXBYE  
    

Input

The input contains between 1 and 10 lines, i-th line contains an integer number xi (0 ≤ xi ≤ 9).

Output

Output a single real number. The answer is considered to be correct if its absolute or relative error does not exceed 10 - 4.

Examples

Input

3
0
1
1


Output

0.666667
#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1000000007;
const long double PI = 2 * acos(0.0);
const vector<long long int> dx = {1, -1, 0, 0};
const vector<long long int> dy = {0, 0, 1, -1};
vector<long long int> ga(long long int n, bool oneIndexed = false) {
  vector<long long int> a;
  if (oneIndexed) a.push_back(0ll);
  for (long long int i = 0; i < n; i++) {
    long long int p;
    cin >> p;
    a.push_back(p);
  }
  return move(a);
}
vector<unsigned long long int> gau(unsigned long long int n,
                                   bool oneIndexed = false) {
  vector<unsigned long long int> a;
  if (oneIndexed) a.push_back(0llu);
  for (unsigned long long int i = 0; i < n; i++) {
    unsigned long long int p;
    cin >> p;
    a.push_back(p);
  }
  return move(a);
}
vector<string> gas(unsigned long long int n, bool oneIndexed = false) {
  vector<string> a;
  if (oneIndexed) a.push_back("");
  for (unsigned long long int i = 0; i < n; i++) {
    string p;
    cin >> p;
    a.push_back(p);
  }
  return move(a);
}
template <typename T, typename A>
void pa(vector<T, A> const &a, long long int begin = 0,
        long long int end = -1) {
  if (end == -1) end = a.size() - 1;
  for (long long int i = begin; i <= end; i++) {
    cout << a[i] << " ";
  }
  cout << "\n";
}
template <typename T, typename A>
void papair(vector<T, A> const &a, long long int begin = 0,
            long long int end = -1) {
  if (end == -1) end = a.size() - 1;
  for (long long int i = begin; i <= end; i++) {
    cout << a[i].first << " " << a[i].second << "\n";
  }
  cout << "\n";
}
void yes() { cout << "YES\n"; }
void no() { cout << "NO\n"; }
void yesno(int f) {
  if (f)
    yes();
  else
    no();
}
void solve() {
  long long int n, m, p, q;
  n = m = p = 0;
  q = 1;
  long long int t;
  cin >> t;
  while (t--) {
    long long int x;
    cin >> x;
    n += x;
    m++;
    if (n * q > m * p) {
      p = n;
      q = m;
    }
  }
  cout << fixed << setprecision(10) << p / (long double)q << "\n";
}
int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
