import java.io.*;
import java.util.ArrayList;
import java.*;
public class Main{
	public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	}
} import java.io.*; io.* java import java.util.ArrayList; ArrayList java.util import java.*; java.* import java.*; public class Main{
	public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	}
} Main public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	} main {
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	} double a=0 a 0 b=0 b 0 c=0 c 0 i=0 i 0 n=0 n 0 j=0 j 0 m=0; m 0 BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); reader new BufferedReader(new InputStreamReader(System.in)) while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  } true {
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  } try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    } catch(Exception e){
      break;
    } Exception e {
      break;
    } break; {
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		} i = 0 i 0 String line = reader.readLine(); line reader.readLine() reader.readLine reader n = Double.parseDouble(line) n Double.parseDouble(line) Double.parseDouble Double line if (n == 0.0) {
        break;
      } n == 0.0 n 0.0 {
        break;
      } break; Double bar[] = new Double[(int)n]; bar new Double[(int)n] (int)n line = reader.readLine() line reader.readLine() reader.readLine reader for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      } String splitted line.split(" ") line.split line " " {
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      } {
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      } bar[(int)i] = Double.parseDouble(splitted) bar[(int)i] bar (int)i Double.parseDouble(splitted) Double.parseDouble Double splitted i++ i a = 0 a 0 for(b=0;b<n;b++){
        a += bar[(int)b];
      } b=0; b=0 b 0 b<n b n b++ b++ b {
        a += bar[(int)b];
      } {
        a += bar[(int)b];
      } a += bar[(int)b] a bar[(int)b] bar (int)b m = a / n m a / n a n c = 0 c 0 for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      } b=0; b=0 b 0 b<n b n b++ b++ b {
        c += Math.pow((bar[(int)b] - m),2);
      } {
        c += Math.pow((bar[(int)b] - m),2);
      } c += Math.pow((bar[(int)b] - m),2) c Math.pow((bar[(int)b] - m),2) Math.pow Math (bar[(int)b] - m) bar[(int)b] bar (int)b m 2 j = c / n j c / n c n System.out.println(String.format("%.8f", Math.sqrt(j))) System.out.println System.out System System.out String.format("%.8f", Math.sqrt(j)) String.format String "%.8f" Math.sqrt(j) Math.sqrt Math j String args[] args public class Main{
	public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	}
} public class Main{
	public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	}
} Main
import java.io.*;
import java.util.ArrayList;
import java.*;
public class Main{
	public static void main(String args[]){
    double a=0,b=0,c=0,i=0,n=0,j=0,m=0;
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));



    while(true){
    try{
      i = 0;
      String line = reader.readLine();
      n = Double.parseDouble(line);
      if (n == 0.0) {
        break;
      }
      Double bar[] = new Double[(int)n];
      line = reader.readLine();
      for(String splitted: line.split(" ")){
        bar[(int)i] = Double.parseDouble(splitted);
        i++;
      }
      a = 0;
      for(b=0;b<n;b++){
        a += bar[(int)b];
      }
      m = a / n;

      c = 0;
      for(b=0;b<n;b++){
        c += Math.pow((bar[(int)b] - m),2);
      }
      j = c / n;
      System.out.println(String.format("%.8f", Math.sqrt(j)));
      





		}catch(Exception e){
      break;
    }





  }



  
	}
}
