import java.util.Scanner;

public class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    }
    
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    }
    
} Main public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        } n != 0 n 0 {
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        } int[] s = new int[n]; s new int[n] n int sum = 0; sum 0 double ave = 0; ave 0 double a = 0; a 0 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 ave = (double) sum / n ave (double) sum / n (double) sum n for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } int j = 0; int j = 0; j 0 j <n j n j++ j++ j {
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } {
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } a += (double)(s[j] - ave)*(s[j] - ave) / n a (double)(s[j] - ave)*(s[j] - ave) / n (double)(s[j] - ave)*(s[j] - ave) (double)(s[j] - ave) s[j] s j ave (s[j] - ave) s[j] s j ave n double b = Math.sqrt(a); b Math.sqrt(a) Math.sqrt Math a System.out.printf("%.8f\n",b) System.out.printf System.out System System.out "%.8f\n" b n = sc.nextInt() n sc.nextInt() sc.nextInt sc sc.close() sc.close sc String[] arg arg public class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    }
    
} public class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    }
    
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n != 0){
            int[] s = new int[n];
            int sum = 0;
            double ave = 0;
            double a = 0;
            for(int i = 0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            ave = (double) sum / n;
            for(int j = 0; j <n; j++){
                a += (double)(s[j] - ave)*(s[j] - ave) / n;
            } 
            double b = Math.sqrt(a);
            System.out.printf("%.8f\n",b);
            n = sc.nextInt();
        }
        sc.close();
    }
    
}
