      
    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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.StringTokenizer;

public class C {
	BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st = null;

	private void solution() throws IOException {
		int tux = 0;
		tux = nextInt();
		int FOO = 0;
		int BAR = 0;
		int BAZ = 0;
		int QUZ = 1;
		while (tux-- > 0) {
			int pur = nextInt();
			FOO += pur;
			BAR++;
			if (Math.max(FOO * QUZ, BAR * BAZ) == FOO * QUZ) {
				BAZ = FOO;
				QUZ = BAR;
			}
		}
		double ans = BAZ * 1.0;
		ans /= QUZ;
		System.out.println(ans);

	}

	String nextToken() throws IOException {
		if (st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(bf.readLine());
		}
		return st.nextToken();
	}

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

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

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

	public void print(int a[]) {
		for (int i = 0; i < a.length; i++) {
			System.out.print(a[i] + " ");
		}
	}

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