      
    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.FileReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Locale;
import java.util.StringTokenizer;

public class c {
    void do_solve() {
        int  tux = nextInt();
        
        long foo = 0;
        long bar = 0;
        long baz = 0;
        long quz = 1;
        
        while (tux != 0) {
            int pur = nextInt();
            foo += pur;
            bar += 1;
            
            if ( Math.max(foo * quz, bar * baz ) == foo * quz ) {
                baz = foo;
                quz = bar;
            } 
            tux--;
            
        //  debug(foo, bar, baz, quz, pur);
        }
        //baz = nextInt();
        out.println(baz / (double)quz);
    }
    
    void mainProgram() {
        init(null);
        int test = 0;
        long T = System.currentTimeMillis();
        do_solve();
        System.err.println("Time on test " + (test++) + ": "
                + (System.currentTimeMillis() - T) + " ms");
        out.close();
    }

    static void debug(Object... o) {
        System.err.println(Arrays.deepToString(o));
    }

    void init(String filename) {
        Locale.setDefault(Locale.US);
        if (filename != null)
            try {
                in = new BufferedReader(new FileReader(filename + ".in"));
                out = new PrintWriter(filename + ".out");
            } catch (Exception e) {
                e.printStackTrace();
                filename = null;
            }
        if (filename == null) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        }
        st = new StringTokenizer("");
    }

    static BufferedReader in;
    static StringTokenizer st = new StringTokenizer("");
    static PrintWriter out;
    static long systemTime;

    public static void main(String[] args) {
        try {
            setTime();
            new c().mainProgram();
            printTime();
            printMemory();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    static void setTime() {
        systemTime = System.currentTimeMillis();
    }

    static void printTime() {
        System.err.println("Time consumed: "
                + (System.currentTimeMillis() - systemTime));
    }

    static void printMemory() {
        System.err.println("Memory consumed: "
                + (Runtime.getRuntime().totalMemory() - Runtime.getRuntime()
                        .freeMemory()) / 1000 + "kb");
    }

    boolean hasMoreTokens() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(in.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return st.hasMoreTokens();
    }

    String nextToken() {
        return hasMoreTokens() ? st.nextToken() : null;
    }

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

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

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

    BigInteger add(BigInteger A, BigInteger B) {
        return A.add(B);
    }

    BigInteger mult(BigInteger A, BigInteger B) {
        return A.multiply(B);
    }

    BigInteger sub(BigInteger A, BigInteger B) {
        return A.subtract(B);
    }

    BigInteger div(BigInteger A, BigInteger B) {
        return A.divide(B);
    }

    BigInteger mi(BigInteger A) {
        return (BigInteger.ZERO).subtract(A);
    }

    BigInteger sq(BigInteger A) {
        return A.multiply(A);
    }

    BigInteger val(long a) {
        return BigInteger.valueOf(a);
    }

    int cmp(BigInteger a, BigInteger b) {
        return a.compareTo(b);
    }

    BigInteger gcd(BigInteger a, BigInteger b) {
        if (cmp(a, val(0)) < 0)
            a = mi(a);
        if (cmp(b, val(0)) < 0)
            b = mi(b);
        return a.gcd(b);
    }
}
