      
    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.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class C implements Runnable {

    /*
    for
     foo := foo + pur
     bar := bar + 1
     ?  foo * quz,  bar * baz,  foo * quz
      baz := foo
      quz := bar

    baz / quz
     */

    public void solve() throws IOException {
        int foo = 0;
        int bar = 0;
        int baz = 0;
        int quz = 1;
        int tux = in.nextInt();
        for ( int i = 0; i < tux; i ++ ) {
            int pur = in.nextInt();
            foo += pur;
            bar += 1;
            if ( baz * bar <= foo * quz ) {
                baz = foo;
                quz = bar;
            }
        }
        out.println( 1.0 * baz / quz );
    }

    public Scanner in;

    public PrintWriter out;

    C() throws IOException {
        in = new Scanner(System.in);
        // in = new StreamTokenizer( new InputStreamReader( System.in ) );
        out = new PrintWriter(System.out);
    }

//    int nextInt() throws IOException {
//        in.nextToken();
//        return ( int ) in.nval;
//    }

    void check(boolean f, String msg) {
        if (!f) {
            out.close();
            throw new RuntimeException(msg);
        }
    }

    void close() throws IOException {
        out.close();
    }

    public void run() {
        try {
            solve();
            close();
        } catch (Exception e) {
            e.printStackTrace(out);
            out.flush();
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) throws IOException {
        new Thread(new C()).start();
    }
}