Problem:       
    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

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;


public class PrC {
	public static void main(String[] args) throws IOException {
		new PrC().run();
	}
	
	BufferedReader in;
	PrintWriter out;
	StringTokenizer st;
	
	String nextToken() throws IOException {
		while(st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(in.readLine());
		}
		return st.nextToken();
	}
	
	int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}
	
	void run() throws IOException {
		in = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out, true);
		solve();
		out.flush();
	}
	
	void solve() throws IOException {
		int tux = nextInt();
		int foo = 0;
		int bar = 0;
		int baz = 0;
		int quz = 1;
		for(int i = tux; i > 0; i--) {
			int pur = nextInt();
			foo = foo + pur;
			bar = bar + 1;
			if(Math.max(foo*quz, bar*baz) == foo*quz) {
				baz = foo;
				quz = bar;
			}
		}
		double baz1 = baz;
		baz1 = baz1/quz;
		out.println(baz1);
	}
}