import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        } true {
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        } int sum=0; sum 0 double m=0.0 m 0.0 a2=0.0 a2 0.0 a1=0.0; a1 0.0 int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int s[] = new int[n]; s new int[n] n if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            } n==0 n 0 {
                break;
            } break; {
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            } for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                    s[i] = sc.nextInt();
                    sum += s[i];
                } {
                    s[i] = sc.nextInt();
                    sum += s[i];
                } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i m = (double)sum/n m (double)sum/n (double)sum n for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                    a1 += (double)(s[i]-m)*(s[i]-m);
                } {
                    a1 += (double)(s[i]-m)*(s[i]-m);
                } a1 += (double)(s[i]-m)*(s[i]-m) a1 (double)(s[i]-m)*(s[i]-m) (double)(s[i]-m) s[i] s i m (s[i]-m) s[i] s i m a2 = a1/n a2 a1/n a1 n System.out.println(Math.sqrt(a2)) System.out.println System.out System System.out Math.sqrt(a2) Math.sqrt Math a2 sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    }
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        while(true){
            int sum=0;
            double m=0.0,a2=0.0,a1=0.0;
            int n = sc.nextInt();
            int s[] = new int[n];

            if(n==0){
                break;
            }else{
                for(int i=0;i<n;i++){
                    s[i] = sc.nextInt();
                    sum += s[i];
                }

                m = (double)sum/n;
                
                for(int i=0;i<n;i++){
                    a1 += (double)(s[i]-m)*(s[i]-m);
                }
                a2 = a1/n;

                System.out.println(Math.sqrt(a2));
            }
        }

        sc.close();
    }
}
