import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int sum1 sum1 sum2; sum2 double m m v v s; s int[] score; score while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        } n != 0 n 0 {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        } sum1 = 0 sum1 0 sum2 = 0 sum2 0 score = new int[n] score new int[n] n for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                score[j] = sc.nextInt();
                sum1 += score[j];
            } {
                score[j] = sc.nextInt();
                sum1 += score[j];
            } score[j] = sc.nextInt() score[j] score j sc.nextInt() sc.nextInt sc sum1 += score[j] sum1 score[j] score j m = (double) sum1 / n m (double) sum1 / n (double) sum1 n for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                sum2 += score[j] * score[j];
            } {
                sum2 += score[j] * score[j];
            } sum2 += score[j] * score[j] sum2 score[j] * score[j] score[j] score j score[j] score j v = (double) sum2 / n - m * m v (double) sum2 / n - m * m (double) sum2 / n (double) sum2 n m * m m m s = Math.sqrt(v) s Math.sqrt(v) Math.sqrt Math v System.out.printf("%f\n", s) System.out.printf System.out System System.out "%f\n" s n = sc.nextInt() n sc.nextInt() sc.nextInt sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int sum1, sum2;
        double m, v, s;
        int[] score;
        while(n != 0) {
            sum1 = 0;
            sum2 = 0;
            score = new int[n];
            for (int j = 0; j < n; j++) {
                score[j] = sc.nextInt();
                sum1 += score[j];
            }
            m = (double) sum1 / n;
            for (int j = 0; j < n; j++) {
                sum2 += score[j] * score[j];
            }
            v = (double) sum2 / n - m * m;
            s = Math.sqrt(v);
            System.out.printf("%f\n", s);
            n = sc.nextInt();
        }
    }
}
