
import java.util.*;
class Main {
	public static void main(String...args) {
		Scanner scan = new Scanner(System.in);

		while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		}
	}
} import java.util.*; util.* java class Main {
	public static void main(String...args) {
		Scanner scan = new Scanner(System.in);

		while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		}
	}
} Main public static void main(String...args) {
		Scanner scan = new Scanner(System.in);

		while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		}
	} main {
		Scanner scan = new Scanner(System.in);

		while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		} true {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		} double heikin = 0; heikin 0 double powM = 0; powM 0 int howM = 0; howM 0 if((howM = scan.nextInt()) == 0 ) {
				break;
			} (howM = scan.nextInt()) == 0 (howM = scan.nextInt()) howM scan.nextInt() scan.nextInt scan 0 {
				break;
			} break; int mem = 0; mem 0 for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			} int i = 0; int i = 0; i 0 i < howM i howM i++ i++ i {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			} {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			} mem = scan.nextInt() mem scan.nextInt() scan.nextInt scan heikin += mem heikin mem powM  +=Math.pow(mem , 2) powM Math.pow(mem , 2) Math.pow Math mem 2 heikin /= howM heikin howM powM  /=howM powM howM Double powH = Math.pow(heikin,2); powH Math.pow(heikin,2) Math.pow Math heikin 2 System.out.println(Math.sqrt(powM - powH)) System.out.println System.out System System.out Math.sqrt(powM - powH) Math.sqrt Math powM - powH powM powH String...args args

import java.util.*;
class Main {
	public static void main(String...args) {
		Scanner scan = new Scanner(System.in);

		while(true) {
		double heikin = 0;
		double powM = 0;
		int howM = 0;
			if((howM = scan.nextInt()) == 0 ) {
				break;
			}
			int mem = 0;
			for(int i = 0; i < howM ; i++) {
				mem = scan.nextInt();
				heikin += mem;
				powM  +=Math.pow(mem , 2);
			}
			heikin /= howM;
		    powM  /=howM;
           Double powH = Math.pow(heikin,2);
			//System.out.println(heikin  + " " + powM);
			System.out.println(Math.sqrt(powM - powH));
		}
	}
}
