      
    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.util.*;

public class Solution {
    public static void main (String[] args) throws IOException {
        boolean online = "true".equals(System.getProperty("ONLINE_JUDGE"));
        if (online) {
            in = new InputReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        }
        else {
            in = new InputReader(new FileReader("input.txt"));
            out = new PrintWriter(new File("output.txt"));
        }
        
        new Solution().run();
        
        out.close();
    }
    
    private void run () {
        boolean it = false;
        int foo = 0,
            bar = 0,
            baz = 0,
            quz = 1,
            tux = in.nextInt();
        for (int i = 0; i < tux; ++i) {
            int pur = in.nextInt();
            foo += pur;
            ++bar;
            it = (foo*quz >= bar*baz);
            if (it) {
                baz = foo;
                quz = bar;
            }
        }
        out.println(baz*1.0/quz);
    }
    
    private static InputReader in;
    private static PrintWriter out;
}

class InputReader {
    public InputReader (Reader r) {
        buff = new BufferedReader(r);
        try {
            str = new StringTokenizer(buff.readLine());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public String next () {
        while (!str.hasMoreTokens())
            try {
                str = new StringTokenizer(buff.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        return str.nextToken();
    }
    
    public int nextInt () {
        return Integer.parseInt(this.next());
    }
    
    public long nextLong () {
        return Long.parseLong(this.next());
    }
    
    private static BufferedReader buff;
    private static StringTokenizer str;
}