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

public class Main {
 
    static final double eps = 1e-8;
    static final int mod = 1000 * 1000 * 1000 + 7;
    static final BigInteger modB = BigInteger.valueOf(mod);
    static int n;

    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        try {
           int tux=sc.nextInt();
           int foo=0;
           int bar=0;
           int baz=0;
           int quz=1;
           for (int i=tux;tux>0;tux--)
           {
               int pur = sc.nextInt();
               foo+=pur;
               bar++;
               if (Math.max(foo*quz,bar*baz)==foo*quz)
               {
                   baz=foo;
                   quz=bar;
               }
           }
           double x = (double)baz/(double)quz;
           pw.println(x);
        }
        
        finally {
            
            pw.close();
        }
    }


     
     
    


    static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st ;
    static PrintWriter pw;
    static int nextInt() throws IOException {
        in.nextToken();
        return (int) in.nval;
    }
    static long nextLong() throws IOException {
        in.nextToken();
        return (long) in.nval;
    }
    static double nextDouble() throws IOException {
        in.nextToken();
        return in.nval;
    }
    static String next() throws IOException {
        in.nextToken();
        return in.sval;
    }
    static void outArray(int[] O) {
        for(int i = 0; i < O.length - 1; i++)
            pw.print(O[i] + " ");
        pw.println(O[O.length - 1]);
    }
    static void exit(Object arg)
    {
        pw.println(arg);
        pw.flush();
        System.exit(0);
    }
}