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

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


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

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


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

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


    } main {
        Scanner sc = new Scanner(System.in);

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) ArrayList<Double> S = new ArrayList<Double>(); S new ArrayList<Double>() while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        } true {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            } n == 0 n 0 {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            } for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                } int i=0; int i=0; i 0 i<S.size() i S.size() S.size S i++ i++ i {
                    System.out.println(S.get(i));
                } {
                    System.out.println(S.get(i));
                } System.out.println(S.get(i)) System.out.println System.out System System.out S.get(i) S.get S i break; int[] A = new int[n]; A new int[n] n int[] B = new int[n]; B new int[n] n double sum1 = 0; sum1 0 double sum2 = 0; sum2 0 for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            } {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            } A[i] = sc.nextInt() A[i] A i sc.nextInt() sc.nextInt sc sum1 += A[i] sum1 A[i] A i sum2 += Math.pow(A[i], 2) sum2 Math.pow(A[i], 2) Math.pow Math A[i] A i 2 double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2)); s Math.sqrt(sum2/n - Math.pow(sum1/n, 2)) Math.sqrt Math sum2/n - Math.pow(sum1/n, 2) sum2/n sum2 n Math.pow(sum1/n, 2) Math.pow Math sum1/n sum1 n 2 S.add(s) S.add S s String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


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

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


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

        ArrayList<Double> S = new ArrayList<Double>();

        while (true) {
            int n = sc.nextInt();

            if (n == 0) {
                for (int i=0; i<S.size(); i++) {
                    System.out.println(S.get(i));
                }
                break;
            }

            int[] A = new int[n];
            int[] B = new int[n];
            double sum1 = 0;
            double sum2 = 0;
            for (int i=0; i<n; i++) {
                A[i] = sc.nextInt();
                sum1 += A[i];
                sum2 += Math.pow(A[i], 2);
            }
            double s = Math.sqrt(sum2/n - Math.pow(sum1/n, 2));

            S.add(s);

        }


    }
}
