import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Main{
  public static void main(String args[]) throws IOException{
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   double alph;

   while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   }


  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io class Main{
  public static void main(String args[]) throws IOException{
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   double alph;

   while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   }


  }
} Main public static void main(String args[]) throws IOException{
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   double alph;

   while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   }


  } main {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   double alph;

   while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   }


  } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) double alph; alph while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   } true {

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   } String st = br.readLine(); st br.readLine() br.readLine br if( st.equals("0") ) break; st.equals("0") st.equals st "0" break; double n = Double.parseDouble( st ); n Double.parseDouble( st ) Double.parseDouble Double st String[] s = br.readLine().split(" "); s br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double sum = 0; sum 0 for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
    	   sum += Double.parseDouble( s[i] );
       } {
    	   sum += Double.parseDouble( s[i] );
       } sum += Double.parseDouble( s[i] ) sum Double.parseDouble( s[i] ) Double.parseDouble Double s[i] s i double ave = sum / n; ave sum / n sum n double sigma = 0; sigma 0 for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       } {
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       } sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) sigma Math.pow(Double.parseDouble( s[i] ) - ave , 2) Math.pow Math Double.parseDouble( s[i] ) - ave Double.parseDouble( s[i] ) Double.parseDouble Double s[i] s i ave 2 alph =Math.sqrt (sigma / n ) alph Math.sqrt (sigma / n ) Math.sqrt Math sigma / n sigma n System.out.println(alph) System.out.println System.out System System.out alph String args[] args
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Main{
  public static void main(String args[]) throws IOException{
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   double alph;

   while(true){

	   String st = br.readLine();
	   if( st.equals("0") ) break;
       double n = Double.parseDouble( st );
       String[] s = br.readLine().split(" ");

       double sum = 0;
       for(int i = 0; i < n ; i++){
    	   sum += Double.parseDouble( s[i] );
       }

       double ave = sum / n;

       double sigma = 0;

       for(int i = 0; i < n ; i++){
    	   sigma += Math.pow(Double.parseDouble( s[i] ) - ave , 2) ;
       }

       alph =Math.sqrt (sigma / n );
       System.out.println(alph);

   }


  }
}