import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n; n String str[]; str StringBuilder sb = new StringBuilder(); sb new StringBuilder() while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        } (n = Integer.parseInt(br.readLine()))!=0 (n = Integer.parseInt(br.readLine())) n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br 0 {
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        } str = br.readLine().split(" ") str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int score[] = new int[n]; score new int[n] n double m = 0 m 0 alpha = 0; alpha 0 for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            } {
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            } score[i] = Integer.parseInt(str[i]) score[i] score i Integer.parseInt(str[i]) Integer.parseInt Integer str[i] str i m += score[i] m score[i] score i m = m / n m m / n m n for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                alpha += Math.pow(score[i]-m, 2);
            } {
                alpha += Math.pow(score[i]-m, 2);
            } alpha += Math.pow(score[i]-m, 2) alpha Math.pow(score[i]-m, 2) Math.pow Math score[i]-m score[i] score i m 2 alpha = alpha / n alpha alpha / n alpha n sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n") sb.append(String.format("%.8f", Math.sqrt(alpha))).append sb.append(String.format("%.8f", Math.sqrt(alpha))) sb.append sb String.format("%.8f", Math.sqrt(alpha)) String.format String "%.8f" Math.sqrt(alpha) Math.sqrt Math alpha "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String str[];
        StringBuilder sb = new StringBuilder();
        while((n = Integer.parseInt(br.readLine()))!=0){
            str = br.readLine().split(" ");
            int score[] = new int[n];
            double m = 0,alpha = 0;
            for(int i=0;i<n;i++){
                score[i] = Integer.parseInt(str[i]);
                m += score[i];
            }
            m = m / n;
            for(int i=0;i<n;i++){
                alpha += Math.pow(score[i]-m, 2);
            }
            alpha = alpha / n;
            sb.append(String.format("%.8f", Math.sqrt(alpha))).append("\n");
        }
        System.out.print(sb);
    }
}