import java.util.*;
public class Main{
    static Scanner kbd = new Scanner(System.in);
    public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    }
} import java.util.*; util.* java public class Main{
    static Scanner kbd = new Scanner(System.in);
    public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    }
} Main static Scanner kbd = new Scanner(System.in); kbd new Scanner(System.in) public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    } main {
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    } while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    } kbd.hasNext() kbd.hasNext kbd {
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    } int n = kbd.nextInt(); n kbd.nextInt() kbd.nextInt kbd if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        } n!=0 n 0 {
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        } int[] s = new int[n]; s new int[n] n double ave = 0; ave 0 int i; i for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        } i=0; i=0 i 0 i<n i n i++ i++ i {
            s[i] = kbd.nextInt();
            ave += s[i];
        } {
            s[i] = kbd.nextInt();
            ave += s[i];
        } s[i] = kbd.nextInt() s[i] s i kbd.nextInt() kbd.nextInt kbd ave += s[i] ave s[i] s i ave = ave/n ave ave/n ave n double a=0; a 0 for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        } i=0; i=0 i 0 i<n i n i++ i++ i {
            a += (s[i]-ave)*(s[i]-ave);
        } {
            a += (s[i]-ave)*(s[i]-ave);
        } a += (s[i]-ave)*(s[i]-ave) a (s[i]-ave)*(s[i]-ave) (s[i]-ave) s[i] s i ave (s[i]-ave) s[i] s i ave a = a/n a a/n a n a = Math.sqrt(a) a Math.sqrt(a) Math.sqrt Math a System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main{
    static Scanner kbd = new Scanner(System.in);
    public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    }
} public class Main{
    static Scanner kbd = new Scanner(System.in);
    public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    }
} Main
import java.util.*;
public class Main{
    static Scanner kbd = new Scanner(System.in);
    public static void main(String[] args){
     
    while(kbd.hasNext()){
        int n = kbd.nextInt();
        if(n!=0){
        int[] s = new int[n];
        double ave = 0;
        int i;
 
        for(i=0; i<n; i++){
            s[i] = kbd.nextInt();
            ave += s[i];
        }
        ave = ave/n;
 
        double a=0;
        for(i=0; i<n; i++){
            a += (s[i]-ave)*(s[i]-ave);
        }
        a = a/n;
        a = Math.sqrt(a);
 
        System.out.println(a);
        }
    }
    }
}