      
    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.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.FileReader;
import java.util.Arrays;
import java.util.Locale;
import java.util.Iterator;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.StringTokenizer;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Abrackadabra
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		OutputWriter out = new OutputWriter(outputStream);
		TaskC solver = new TaskC();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskC {
    public void solve(int testNumber, InputReader in, OutputWriter out) {
        int tux = in.nextInt();
        int foo = 0;
        int bar = 0;
        int baz = 0;
        int quz = 1;

        for (int i = 0; i < tux; i++) {
            int pur = in.nextInt();

            foo += pur;
            bar++;

            if (Math.max(foo * quz, bar * baz) == foo * quz) {
                baz = foo;
                quz = bar;
            }
        }

        out.println(1d * baz / quz);
    }
}

class InputReader implements Iterable<String> {
    BufferedReader br;
    StringTokenizer in;

    public InputReader(String fileName) {
        try {
            br = new BufferedReader(new FileReader(fileName));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public InputReader(InputStream inputStream) {
        br = new BufferedReader(new InputStreamReader(inputStream));
    }

    String lastLine = null;

    boolean hasMoreTokens() {
        while (in == null || !in.hasMoreTokens()) {
            lastLine = nextLine();
            if (lastLine == null) {
                return false;
            }
            in = new StringTokenizer(lastLine);
        }
        return true;
    }

    public String nextString() {
        return hasMoreTokens() ? in.nextToken() : null;
    }

    public String nextLine() {
        boolean somethingLeft = in != null && in.hasMoreTokens();
        in = null;
        if (somethingLeft) {
            return lastLine;
        }
        try {
            return br.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public int nextInt() {
        return Integer.parseInt(nextString());
    }

    public Iterator<String> iterator() {
        return new Iterator<String>() {
            @Override
            public boolean hasNext() {
                return hasMoreTokens();
            }

            @Override
            public String next() {
                return nextString();
            }

            @Override
            public void remove() {
                throw new RuntimeException();
            }
        };
    }
}

class OutputWriter {

    final PrintWriter out;

    public OutputWriter(String fileName) {
        try {
            out = new PrintWriter(fileName);
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        }
    }

    public OutputWriter(OutputStream outputStream) {
        out = new PrintWriter(outputStream);
    }

    public OutputWriter(Writer writer) {
        out = new PrintWriter(writer);
    }

    /* PrintWriter methods */

    public void close() {
        out.close();
    }

    public void println(double x) {
        out.println(x);
    }

    /* My helper methods */

    }

