import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        } true {
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        } double sum1=0 sum1 0 sum2=0 sum2 0 ave=0 ave 0 bun=0 bun 0 hen=0; hen 0 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 for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            } {
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            } data[i] = sc.nextInt() data[i] data i sc.nextInt() sc.nextInt sc sum1 += (double)data[i] sum1 (double)data[i] data i ave = sum1/n ave sum1/n sum1 n for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                sum2 += (data[i]-ave)*(data[i]-ave);
            } {
                sum2 += (data[i]-ave)*(data[i]-ave);
            } sum2 += (data[i]-ave)*(data[i]-ave) sum2 (data[i]-ave)*(data[i]-ave) (data[i]-ave) data[i] data i ave (data[i]-ave) data[i] data i ave bun = sum2/n bun sum2/n sum2 n hen = Math.sqrt(bun) hen Math.sqrt(bun) Math.sqrt Math bun System.out.println(hen) System.out.println System.out System System.out hen String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            double sum1=0, sum2=0, ave=0, bun=0, hen=0;
            int n = sc.nextInt();
            if(n==0) break;
            int[] data = new int[n];
            for(int i=0;i<n;i++){
                data[i] = sc.nextInt();
                sum1 += (double)data[i];
            }
            ave = sum1/n;
            for(int i=0;i<n;i++){
                sum2 += (data[i]-ave)*(data[i]-ave);
            }
            bun = sum2/n;
            hen = Math.sqrt(bun);
            System.out.println(hen);
        }
    }
}
