import java.util.Scanner;

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

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