import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    }
} Main public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    } main {
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    } int sum = 0; sum 0 double ave; ave double s = 0; s 0 Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        } true {
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        } int Length = sc.nextInt(); Length sc.nextInt() sc.nextInt sc if(Length == 0){
                break;
            } Length == 0 Length 0 {
                break;
            } break; int[] number = new int[Length]; number new int[Length] Length for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            } int i=0; int i=0; i 0 i<Length i Length i++ i++ i {
                number[i] = sc.nextInt();
                sum += number[i];
            } {
                number[i] = sc.nextInt();
                sum += number[i];
            } number[i] = sc.nextInt() number[i] number i sc.nextInt() sc.nextInt sc sum += number[i] sum number[i] number i ave = (double) sum / Length ave (double) sum / Length (double) sum Length for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            } int i=0; int i=0; i 0 i<Length i Length i++ i++ i {
                s += (number[i] - ave)*(number[i] - ave);
            } {
                s += (number[i] - ave)*(number[i] - ave);
            } s += (number[i] - ave)*(number[i] - ave) s (number[i] - ave)*(number[i] - ave) (number[i] - ave) number[i] number i ave (number[i] - ave) number[i] number i ave s /= Length s Length s = Math.sqrt(s) s Math.sqrt(s) Math.sqrt Math s System.out.println(s) System.out.println System.out System System.out s s = 0 s 0 sum = 0 sum 0 sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    }
} public class Main {
    public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        int sum = 0;
        double ave;
        double s = 0;
        Scanner sc = new Scanner(System.in);
        while(true){
            int Length = sc.nextInt();
            if(Length == 0){
                break;
            }
            int[] number = new int[Length];
            for(int i=0; i<Length; i++){
                number[i] = sc.nextInt();
                sum += number[i];
            }
            ave = (double) sum / Length;

            for(int i=0; i<Length; i++){
                s += (number[i] - ave)*(number[i] - ave);
            }
            s /= Length;
            s = Math.sqrt(s);
            //System.out.printf("%d", number[i]);
            System.out.println(s);
            s = 0;
            sum = 0;
        }
        sc.close();
    }
}
