import java.math.BigDecimal;
import java.util.Scanner;

//Solution:

public class Main {  
  public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    }
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {  
  public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    }
} Main public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    } main {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    } Scanner f = new Scanner(System.in); f new Scanner(System.in) while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        } true {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        } int num = f.nextInt(); num f.nextInt() f.nextInt f if(num == 0) break; num == 0 num 0 break; BigDecimal[] entries = new BigDecimal[num]; entries new BigDecimal[num] num BigDecimal sum = new BigDecimal(0); sum new BigDecimal(0) BigDecimal std = new BigDecimal(0); std new BigDecimal(0) for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            } {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            } BigDecimal temp = new BigDecimal(f.nextInt()); temp new BigDecimal(f.nextInt()) entries[i] = temp entries[i] entries i temp sum = sum.add(temp) sum sum.add(temp) sum.add sum temp BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP); average sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP) sum.divide sum new BigDecimal(num) 6 BigDecimal.ROUND_HALF_UP BigDecimal BigDecimal.ROUND_HALF_UP for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
                std = std.add(entries[i].subtract(average).pow(2));
            } {
                std = std.add(entries[i].subtract(average).pow(2));
            } std = std.add(entries[i].subtract(average).pow(2)) std std.add(entries[i].subtract(average).pow(2)) std.add std entries[i].subtract(average).pow(2) entries[i].subtract(average).pow entries[i].subtract(average) entries[i].subtract entries[i] entries i average 2 System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue())) System.out.println System.out System System.out Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()) Math.sqrt Math std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue() std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP) std.divide std new BigDecimal(num) 6 BigDecimal.ROUND_HALF_UP BigDecimal BigDecimal.ROUND_HALF_UP String[] args args public class Main {  
  public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    }
} public class Main {  
  public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    }
} Main
import java.math.BigDecimal;
import java.util.Scanner;

//Solution:

public class Main {  
  public static void main(String[] args) {
        Scanner f = new Scanner(System.in);
        // fill in the dictionary with the initial value
         while(true) {
            int num = f.nextInt();
            if(num == 0) break;
            BigDecimal[] entries = new BigDecimal[num];
            BigDecimal sum = new BigDecimal(0);
            BigDecimal std = new BigDecimal(0);
            for (int i = 0; i < num; i++) {
                BigDecimal temp = new BigDecimal(f.nextInt());
                entries[i] = temp;
                sum = sum.add(temp);
            }
            BigDecimal average = sum.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP);
            for (int i = 0; i < num; i++) {
                std = std.add(entries[i].subtract(average).pow(2));
            }
            System.out.println(Math.sqrt(std.divide(new BigDecimal(num),6, BigDecimal.ROUND_HALF_UP).doubleValue()));
        }
    }
}
