import java.text.DecimalFormat;
import java.util.Scanner;
public class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    }
} import java.text.DecimalFormat; DecimalFormat java.text import java.util.Scanner; Scanner java.util public class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    }
} Main static Scanner sc = new Scanner(System.in); sc new Scanner(System.in) public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    } main {
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    } DecimalFormat df1 = new DecimalFormat("0.########"); df1 new DecimalFormat("0.########") DecimalFormat df2 = new DecimalFormat("0.00000000"); df2 new DecimalFormat("0.00000000") while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		} sc.hasNext() sc.hasNext sc {
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		} int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			} n!=0 n 0 {
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(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] = sc.nextInt();
					ave += s[i];
				} i=0; i=0 i 0 i<n i n i++ i++ i {
					s[i] = sc.nextInt();
					ave += s[i];
				} {
					s[i] = sc.nextInt();
					ave += s[i];
				} s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc 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 if(a > 0){
					System.out.println(df1.format(a));
				} a > 0 a 0 {
					System.out.println(df1.format(a));
				} System.out.println(df1.format(a)) System.out.println System.out System System.out df1.format(a) df1.format df1 a if(a == 0){
					System.out.println(df2.format(a));
				} a == 0 a 0 {
					System.out.println(df2.format(a));
				} System.out.println(df2.format(a)) System.out.println System.out System System.out df2.format(a) df2.format df2 a String[] args args public class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    }
} public class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    }
} Main
import java.text.DecimalFormat;
import java.util.Scanner;
public class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		DecimalFormat df1 = new DecimalFormat("0.########");
		DecimalFormat df2 = new DecimalFormat("0.00000000");
		
		while(sc.hasNext()){
			int n = sc.nextInt();
			if(n!=0){
				int[] s = new int[n];
				double ave = 0;
				int i;
				
				for(i=0; i<n; i++){
					s[i] = sc.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);
				
				if(a > 0){
					System.out.println(df1.format(a));
				}
				if(a == 0){
					System.out.println(df2.format(a));
				}
			}
		}
    }
}
