import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        } true {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n == 0) {
                break;
            } n == 0 n 0 {
                break;
            } break; double[] score = new double[n]; score new double[n] n double sum = 0.0; sum 0.0 for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                score[i] = sc.nextDouble();
                sum += score[i];
            } {
                score[i] = sc.nextDouble();
                sum += score[i];
            } score[i] = sc.nextDouble() score[i] score i sc.nextDouble() sc.nextDouble sc sum += score[i] sum score[i] score i double avg = sum / n; avg sum / n sum n double nSum = 0.0; nSum 0.0 for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                nSum += Math.pow(score[i]-avg, 2);
            } {
                nSum += Math.pow(score[i]-avg, 2);
            } nSum += Math.pow(score[i]-avg, 2) nSum Math.pow(score[i]-avg, 2) Math.pow Math score[i]-avg score[i] score i avg 2 double tmp = nSum / n; tmp nSum / n nSum n System.out.println(String.format("%.9f",Math.sqrt(tmp))) System.out.println System.out System System.out String.format("%.9f",Math.sqrt(tmp)) String.format String "%.9f" Math.sqrt(tmp) Math.sqrt Math tmp sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
            int n = sc.nextInt();
            if(n == 0) {
                break;
            }

            double[] score = new double[n];

            double sum = 0.0;
            for(int i=0; i<n; i++) {
                score[i] = sc.nextDouble();
                sum += score[i];
            }

            double avg = sum / n;

            double nSum = 0.0;
            for(int i=0; i<n; i++) {
                nSum += Math.pow(score[i]-avg, 2);
            }

            double tmp = nSum / n;
            System.out.println(String.format("%.9f",Math.sqrt(tmp)));
        }
        sc.close();
    }
}

