      
    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;
inline long long readInt() {
  register int c = getchar();
  long long x = 0, neg = 0;
  for (; ((c < 48 || c > 57) && c != '-'); c = getchar())
    ;
  if (c == '-') {
    neg = 1;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) x = (x << 1) + (x << 3) + c - 48;
  return (neg) ? -x : x;
}
inline void printInt(long long x) {
  char pri[30];
  int i = 0;
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  do {
    pri[i++] = (x % 10) + 48;
    x /= 10;
  } while (x != 0);
  for (int j = (i - 1); j > (0 - 1); j -= 1) putchar(pri[j]);
}
void solve() {
  int tux;
  cin >> tux;
  int FOO = 0;
  int BAR = 0;
  double ANS = 0;
  while (tux--) {
    int pur;
    cin >> pur;
    FOO += pur;
    BAR += 1;
    ANS = max(FOO / (double)BAR, ANS);
  }
  printf("%0.10f\n", ANS);
}
int main() {
  if (0) {
    double _time = clock();
    freopen("input.txt", "r", stdin);
    solve();
    printf("%0.4f sec\n", (clock() - _time) / CLOCKS_PER_SEC);
    return 0;
  }
  solve();
  return 0;
}
