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

public class Solurion {

	private void solve() throws Exception {
		/*int n = nextInt();
		double sum = 0;
		for (int i = 0; i < n; ++i) {
			sum += nextInt();
		}
		out.println(sum / n);*/
		int tux = nextInt();
		int foo = 0;
		int bar = 0;
		int baz = 0;
		int quz = 1;
		/*if (foo * quz >= bar * baz ) 
		//if (foo * quz * bar)
		{
			System.out.println("YUP");
		} else {
			System.out.println("NO");
		}*/
		for (int i = 0; i < tux; ++i) {
			int pur = nextInt();
			foo = foo + pur;
			bar = bar + 1;
			if (foo * quz >= bar * baz ) 
			{
				baz = foo;
				quz = bar;
			}
		}
		out.println((double) baz / quz);
	}

	public void run() {
		try {
			solve();
		} catch (Exception e) {
			NOO(e);
		} finally {
			out.close();
		}
	}

	PrintWriter out;
	BufferedReader in;
	StringTokenizer St;

	void NOO(Exception e) {
		e.printStackTrace();
		System.exit(42);
	}

	int nextInt() {
		return Integer.parseInt(nextToken());
	}

	long nextLong() {
		return Long.parseLong(nextToken());
	}

	double nextDouble() {
		return Double.parseDouble(nextToken());
	}

	String nextToken() {
		while (!St.hasMoreTokens()) {
			try {
				String line = in.readLine();
				if (line == null)
					return null;
				St = new StringTokenizer(line);
			} catch (Exception e) {
				NOO(e);
			}
		}
		return St.nextToken();
	}

	private Solurion(String name) {
		try {
			in = new BufferedReader(new FileReader("input.txt"));
			St = new StringTokenizer("");
			out = new PrintWriter(new FileWriter("output.txt"));
		} catch (Exception e) {
			NOO(e);
		}
	}

	private Solurion() {
		try {
			in = new BufferedReader(new InputStreamReader(System.in));
			St = new StringTokenizer("");
			out = new PrintWriter(System.out);
		} catch (Exception e) {
			NOO(e);
		}
	}

	public static void main(String[] args) {
		//Locale.setDefault(Locale.US);
		new Solurion().run();
	}
}
