      
    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.io.PrintWriter;
import java.util.StringTokenizer;

public class Main implements Runnable {

	private void solve() throws IOException {
		int 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;
			}
			--tux;
		}

		out.println((baz + .0) / quz);
	}

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

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

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

	String next() throws IOException {
		while (!st.hasMoreTokens()) {
			String line = in.readLine();
			if (line == null)
				return null;
			eat(line);
		}
		return st.nextToken();
	}

	public static void main(String[] args) {
		new Thread(null, new Main(), "Main", 1 << 28).start();
	}

	private BufferedReader in;
	private PrintWriter out;
	private StringTokenizer st;

	@Override
	public void run() {
		try {
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(System.out);
			eat("");
			solve();
			in.close();
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
			System.exit(566);
		}
	}

	private void eat(String s) {
		st = new StringTokenizer(s);
	}

}