Problem:       
    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

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
__inline bool nextInt(int &val) {
  char ch;
  int sgn = 1;
  while ((ch = getchar()) != EOF) {
    if (ch == '-') sgn = -1;
    if (ch >= '0' && ch <= '9') break;
  }
  if (ch == EOF) return false;
  val = (int)(ch - '0');
  while (true) {
    ch = getchar();
    if (ch >= '0' && ch <= '9') {
      val = 10 * val + (int)(ch - '0');
    } else
      break;
  }
  val *= sgn;
  return true;
}
__inline bool nextString(string &s) {
  char ch;
  while ((ch = getchar()) != EOF) {
    if (ch >= 33 && ch <= 126) break;
  }
  if (ch == EOF) return false;
  s = string(1, ch);
  while (true) {
    ch = getchar();
    if (ch >= 33 && ch <= 126) {
      s = s + string(1, ch);
    } else
      break;
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  int tux, pur, foo = 0, bar = 0, baz = 0, quz = 1;
  cin >> tux;
  for (int i = 0; i < (tux); i++) {
    cin >> pur;
    foo += pur;
    bar++;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  cout << fixed << setprecision(10) << 1.0 * baz / quz << endl;
  return 0;
}