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