import java.util.*;
public class Main{
    public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    } main {
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


} true {
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


} int n=0 n 0 i i j; j double sum=0 sum 0 a=0 a 0 b=0; b 0 n=sc.nextInt() n sc.nextInt() sc.nextInt sc if(n==0){
        break;
    } n==0 n 0 {
        break;
    } break; int []d =new int[n]; d new int[n] n for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    } i=0; i=0 i 0 i<n i n i++ i++ i {
        d[i]=sc.nextInt();
        sum=sum+d[i];
    } {
        d[i]=sc.nextInt();
        sum=sum+d[i];
    } d[i]=sc.nextInt() d[i] d i sc.nextInt() sc.nextInt sc sum=sum+d[i] sum sum+d[i] sum d[i] d i sum=sum/n sum sum/n sum n for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    } j=0; j=0 j 0 j<n j n j++ j++ j {
        a = a+ Math.pow(d[j]-sum,2);
    } {
        a = a+ Math.pow(d[j]-sum,2);
    } a = a+ Math.pow(d[j]-sum,2) a a+ Math.pow(d[j]-sum,2) a Math.pow(d[j]-sum,2) Math.pow Math d[j]-sum d[j] d j sum 2 a= a/n a a/n a n b=Math.sqrt(a) b Math.sqrt(a) Math.sqrt Math a System.out.println(b) System.out.println System.out System System.out b String[] args args public class Main{
    public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    }
} public class Main{
    public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    }
} Main
import java.util.*;
public class Main{
    public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    while(true){
    int n=0,i,j;
    double sum=0,a=0,b=0;
    n=sc.nextInt();
    if(n==0){
        break;
    }
    int []d =new int[n];
    for(i=0;i<n;i++){
        d[i]=sc.nextInt();
        sum=sum+d[i];
    }
    sum=sum/n;
    for(j=0;j<n;j++){
        a = a+ Math.pow(d[j]-sum,2);
    }
        a= a/n;
        b=Math.sqrt(a);
    
    System.out.println(b);


}

    }
}
