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 JAVA):

Solution:
import java.io.*;
import java.math.*;
import java.util.*;

public class c {
  public static void main(String[] args) throws Throwable {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    int tux = Integer.parseInt(in.readLine());
    int foo = 0, bar = 0, baz = 0, quz = 1;
    for (int i = tux; i > 0; i--) {
      int pur = Integer.parseInt(in.readLine());
      foo += pur;
      bar++;
      if (foo * quz >= bar * baz) {
        baz = foo;
        quz = bar;
      }
    }
    System.out.println(baz * 1.0 / quz);
  }
}