      
    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.util.Scanner;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.math.BigDecimal;
import java.io.BufferedWriter;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.math.BigInteger;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Fish <lyhypacm@gmail.com>
 */
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 n = in.nextInt();
        int foo = 0, bar = 0, baz = 0, quz = 1;
        for (int i = 0; i < n; ++i) {
            int pur = in.nextInt();
            foo += pur;
            ++bar;
            if (foo * quz >= bar * baz) {
                baz = foo;
                quz = bar;
            } else break;
        }
        out.println(1.0 * baz / quz);
    }
}

class InputReader {
    private Scanner scanner;

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

    public int nextInt() {
        return scanner.nextInt();
    }

    public long nextLong() {
        return scanner.nextLong();
    }

    public String next() {
        return scanner.next();
    }

    public BigInteger nextBigInteger() {
        return scanner.nextBigInteger();
    }

    public BigDecimal nextBigDecimal() {
        return scanner.nextBigDecimal();
    }

    public double nextDouble() {
        return scanner.nextDouble();
    }
}

class OutputWriter {
    private PrintWriter printWriter;

    public OutputWriter(OutputStream outputStream) {
        printWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }

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

    public <T> void print(T object) {
        printWriter.print(object);
    }

    public <T> void println(T object) {
        printWriter.println(object);
    }

    public void println() {
        printWriter.println();
    }

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