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));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    }
} 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));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String line; line while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        } !(line = br.readLine()).equals("0") (line = br.readLine()).equals("0") (line = br.readLine()).equals (line = br.readLine()) line br.readLine() br.readLine br "0" {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        } String[] lines = br.readLine().split(" "); lines br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double[] list = new double[lines.length]; list new double[lines.length] lines.length lines lines.length int n = lines.length; n lines.length lines lines.length double total = 0.0; total 0.0 double average = 0.0; average 0.0 double var = 0.0; var 0.0 while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            } n-- > 0 n-- n 0 {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            } list[n] = Double.parseDouble(lines[n]) list[n] list n Double.parseDouble(lines[n]) Double.parseDouble Double lines[n] lines n total+=list[n] total list[n] list n n=lines.length n lines.length lines lines.length average=total/n average total/n total n for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                var+=((list[i]-average)*(list[i]-average));
            } {
                var+=((list[i]-average)*(list[i]-average));
            } var+=((list[i]-average)*(list[i]-average)) var ((list[i]-average)*(list[i]-average)) (list[i]-average) list[i] list i average (list[i]-average) list[i] list i average System.out.printf("%f\n",Math.sqrt(var/n)) System.out.printf System.out System System.out "%f\n" Math.sqrt(var/n) Math.sqrt Math var/n var n String[] args args public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    }
} public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    }
} 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));
        String line;
        while (!(line = br.readLine()).equals("0")) {
            String[] lines = br.readLine().split(" ");
            double[] list = new double[lines.length];
            int n = lines.length;
            double total = 0.0; //????¨????
            double average = 0.0; //?????????
            double var = 0.0; //?????£
            while (n-- > 0) {
                list[n] = Double.parseDouble(lines[n]);
                total+=list[n];
            }
            n=lines.length;
            average=total/n;
            for(int i=0;i<n;i++){
                var+=((list[i]-average)*(list[i]-average));
            }
            System.out.printf("%f\n",Math.sqrt(var/n));
        }
    }
}