import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[] tokuten; tokuten int kazu = 0; kazu 0 double average = 0; average 0 double hensa2 =0.0; hensa2 0.0 double bunsan; bunsan while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		} true {
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		} kazu = sc.nextInt() kazu sc.nextInt() sc.nextInt sc if(0==kazu) break; 0==kazu 0 kazu break; tokuten = new int[kazu] tokuten new int[kazu] kazu for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			} int i=0; int i=0; i 0 i<tokuten.length i tokuten.length tokuten tokuten.length i++ i++ i {
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			} {
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			} tokuten[i]=sc.nextInt() tokuten[i] tokuten i sc.nextInt() sc.nextInt sc average += (double)tokuten[i]/tokuten.length average (double)tokuten[i]/tokuten.length (double)tokuten[i] tokuten i tokuten.length tokuten tokuten.length for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			} int i=0; int i=0; i 0 i<tokuten.length i tokuten.length tokuten tokuten.length i++ i++ i {
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			} {
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			} hensa2 += (tokuten[i]-average)*(tokuten[i]-average) hensa2 (tokuten[i]-average)*(tokuten[i]-average) (tokuten[i]-average) tokuten[i] tokuten i average (tokuten[i]-average) tokuten[i] tokuten i average bunsan=hensa2/tokuten.length bunsan hensa2/tokuten.length hensa2 tokuten.length tokuten tokuten.length System.out.println(Math.sqrt(bunsan)) System.out.println System.out System System.out Math.sqrt(bunsan) Math.sqrt Math bunsan average = 0 average 0 hensa2 = 0 hensa2 0 kazu =0 kazu 0 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] tokuten;
		int kazu = 0;
		double average = 0;
		double hensa2 =0.0;
		double bunsan;
		while (true){
			kazu = sc.nextInt();
			if(0==kazu) break;
			tokuten = new int[kazu];
			for(int i=0;i<tokuten.length;i++){
				tokuten[i]=sc.nextInt();
				//System.out.println();
				//System.out.println(tokuten[i]);
				average += (double)tokuten[i]/tokuten.length;
			}
			//System.out.println("average = "+average);
			for(int i=0;i<tokuten.length;i++){
				hensa2 += (tokuten[i]-average)*(tokuten[i]-average);
				//System.out.println("hensa2[0~"+i+"] = "+hensa2);
			}
			bunsan=hensa2/tokuten.length;
			//System.out.println("bunsan = "+bunsan);
			System.out.println(Math.sqrt(bunsan));

			/* 初期化 */
			average = 0;
			hensa2 = 0;
			kazu =0;
		}
	}
}
