import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int i; i while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        } true {
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n == 0) break; n == 0 n 0 break; int data[] = new int[n]; data new int[n] n double ave = 0 ave 0 dev = 0; dev 0 for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                data[i] = sc.nextInt();
                ave += data[i];
            } {
                data[i] = sc.nextInt();
                ave += data[i];
            } data[i] = sc.nextInt() data[i] data i sc.nextInt() sc.nextInt sc ave += data[i] ave data[i] data i ave /= n ave n for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                dev += (data[i] - ave)*(data[i] - ave);
            } {
                dev += (data[i] - ave)*(data[i] - ave);
            } dev += (data[i] - ave)*(data[i] - ave) dev (data[i] - ave)*(data[i] - ave) (data[i] - ave) data[i] data i ave (data[i] - ave) data[i] data i ave dev = Math.sqrt(dev/n) dev Math.sqrt(dev/n) Math.sqrt Math dev/n dev n System.out.println(dev) System.out.println System.out System System.out dev String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int i;
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int data[] = new int[n];
            double ave = 0,dev = 0;
            for (i=0;i<n;i++) {
                data[i] = sc.nextInt();
                ave += data[i];
            }
            ave /= n;
            for (i=0;i<n;i++) {
                dev += (data[i] - ave)*(data[i] - ave);
            }
            dev = Math.sqrt(dev/n);
            System.out.println(dev);
        }
    }
}

