      
    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.util.*;
public class C {
	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
													// HAI
		int TUX;        							// I HAS A TUX
		TUX=in.nextInt();   						// GIMMEH TUX   
		int FOO=0;									//I HAS A FOO ITS 0
		int BAR=0;									//I HAS A BAR ITS 0
		int BAZ=0;									//I HAS A BAZ ITS 0
		int QUZ=1;									//I HAS A QUZ ITS 1
													//TUX IS NOW A NUMBR
		for(;TUX!=0;TUX--){ 						//IM IN YR LOOP NERFIN YR TUX TIL BOTH SAEM TUX AN 0
			int PUR;								//I HAS A PUR
			PUR=in.nextInt();						//GIMMEH PUR
													//PUR IS NOW A NUMBR
			FOO+=PUR;								//FOO R SUM OF FOO AN PUR
			BAR++;									//BAR R SUM OF BAR AN 1
			if(FOO*QUZ>=BAR*BAZ){
													//O RLY?
													//YA RLY
				BAZ=FOO;							//BAZ R FOO
				QUZ=BAR;							//QUZ R BAR
			}
													//OIC
		}											//IM OUTTA YR LOOP
													//BAZ IS NOW A NUMBAR
		System.out.println((double)BAZ/QUZ);				//VISIBLE SMOOSH QUOSHUNT OF BAZ QUZ
													//KTHXBYE
	}

}