      
    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.IOException;
import java.util.Scanner;

public class TC2
{
    public static void main( String[] args ) throws IOException
    {
        Scanner s=new Scanner( System.in );
        int N=s.nextInt();
        
        int foo=0, bar=0, baz=0, quz=1;
        
        for( int i=0; i<N; i++ )
        {
            int pur=s.nextInt();
            foo=foo+pur;
            bar++;
            if( Math.max( foo*quz, bar*baz ) == foo*quz )
            {
                baz=foo;
                quz=bar;
            }
        }
        
        double res=1.0*baz/quz;
        System.out.println(res );
    }
    
    
}