import java.util.Scanner;

class Main{
	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		double s[]=new double[1000],t1,t2;
		int n,i;
		while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		}
		scan.close();
	}
} import java.util.Scanner; Scanner java.util class Main{
	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		double s[]=new double[1000],t1,t2;
		int n,i;
		while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		}
		scan.close();
	}
} Main public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		double s[]=new double[1000],t1,t2;
		int n,i;
		while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		}
		scan.close();
	} main {
		Scanner scan=new Scanner(System.in);
		double s[]=new double[1000],t1,t2;
		int n,i;
		while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		}
		scan.close();
	} Scanner scan=new Scanner(System.in); scan new Scanner(System.in) double s[]=new double[1000] s new double[1000] 1000 t1 t1 t2; t2 int n n i; i while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		} true {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		} n=scan.nextInt() n scan.nextInt() scan.nextInt scan if(n==0) break; n==0 n 0 break; t1=0 t1 0 for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			} i=0; i=0 i 0 i<n i n i++ i++ i {
				s[i]=scan.nextDouble();
				t1+=s[i];
			} {
				s[i]=scan.nextDouble();
				t1+=s[i];
			} s[i]=scan.nextDouble() s[i] s i scan.nextDouble() scan.nextDouble scan t1+=s[i] t1 s[i] s i t1/=n t1 n t2=0 t2 0 for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2); i=0; i=0 i 0 i<n i n i++ i++ i t2+=Math.pow(s[i]-t1, 2); t2+=Math.pow(s[i]-t1, 2) t2 Math.pow(s[i]-t1, 2) Math.pow Math s[i]-t1 s[i] s i t1 2 System.out.println(Math.sqrt(t2/n)) System.out.println System.out System System.out Math.sqrt(t2/n) Math.sqrt Math t2/n t2 n scan.close() scan.close scan String[] args args
import java.util.Scanner;

class Main{
	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		double s[]=new double[1000],t1,t2;
		int n,i;
		while(true) {
			n=scan.nextInt();
			if(n==0) break;
			t1=0;
			for(i=0;i<n;i++) {
				s[i]=scan.nextDouble();
				t1+=s[i];
			}
			t1/=n;
			t2=0;
			for(i=0;i<n;i++) t2+=Math.pow(s[i]-t1, 2);
			System.out.println(Math.sqrt(t2/n));
		}
		scan.close();
	}
}
