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:
public class Problem290C {
    public static void main(String[] args){
        java.util.Scanner in = new java.util.Scanner(System.in);
        
        int tux = Integer.parseInt(in.nextLine());
        int foo = 0;
        int bar = 0;
        int baz = 0;
        int quz = 1;
        
        for(; tux > 0; tux--){
            int pur = Integer.parseInt(in.nextLine());
            foo = foo + pur;
            bar++;
            
            if(foo*quz >= bar*baz){
                baz = foo;
                quz = bar;
            }
        }
        
        System.out.println((double)baz / quz);
    }
}