import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    }
    
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    }
    
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        } true {
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        } int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc if(a==0) {break;} a==0 a 0 {break;} break; int []scores=new int[a]; scores new int[a] a 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 average=0 average 0 variance=0 variance 0 deviation=0; deviation 0 int sum=0; sum 0 for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        } int j=0; int j=0; j 0 j<scores.length j scores.length scores scores.length j++ j++ j {
            sum=scores[j]+sum;
        } {
            sum=scores[j]+sum;
        } sum=scores[j]+sum sum scores[j]+sum scores[j] scores j sum average=(double)sum/scores.length average (double)sum/scores.length (double)sum scores.length scores scores.length for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        } int k=0; int k=0; k 0 k<scores.length k scores.length scores scores.length k++ k++ k {
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        } {
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        } deviation=deviation+(scores[k]-average)*(scores[k]-average) deviation deviation+(scores[k]-average)*(scores[k]-average) deviation (scores[k]-average)*(scores[k]-average) (scores[k]-average) scores[k] scores k average (scores[k]-average) scores[k] scores k average variance=deviation/scores.length variance deviation/scores.length deviation scores.length scores scores.length System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance 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 a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    }
    
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    }
    
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
            if(a==0) {break;}
            int []scores=new int[a];
            for(int i=0;i<scores.length;i++){
                scores[i] = sc.nextInt();
            } 
        double average=0,variance=0,deviation=0;
        int sum=0;
        for(int j=0;j<scores.length;j++){
            sum=scores[j]+sum;
        }
        average=(double)sum/scores.length;

        for(int k=0;k<scores.length;k++){
            deviation=deviation+(scores[k]-average)*(scores[k]-average);
        }  
            variance=deviation/scores.length;
    
        System.out.println(Math.sqrt(variance));

        }
sc.close();
    }
    
}
