import java.util.Scanner;

public class Main{
  public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  }
} Main public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  } main {
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  } try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   } {
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     } true {
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n == 0){
	break;
      } n == 0 n 0 {
	break;
      } break; int[]score = new int[n]; score new int[n] n for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
	score[i] = sc.nextInt();
	} {
	score[i] = sc.nextInt();
	} score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc double average = 0 average 0 variance = 0; variance 0 for(int i = 0;i < n;i++){
	average = average+score[i];
	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
	average = average+score[i];
	} {
	average = average+score[i];
	} average = average+score[i] average average+score[i] average score[i] score i average = average/n average average/n average n for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
	variance = (score[i]-average)*(score[i]-average)+variance;
	} {
	variance = (score[i]-average)*(score[i]-average)+variance;
	} variance = (score[i]-average)*(score[i]-average)+variance variance (score[i]-average)*(score[i]-average)+variance (score[i]-average)*(score[i]-average) (score[i]-average) score[i] score i average (score[i]-average) score[i] score i average variance variance = variance/n variance variance/n variance n System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance String[]args args public class Main{
  public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  }
} public class Main{
  public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  }
} Main
import java.util.Scanner;

public class Main{
  public static void main(String[]args){
   
   try(Scanner sc = new Scanner(System.in)){
      while(true){
       int n = sc.nextInt();
      if(n == 0){
	break;
      }
	int[]score = new int[n];
	for(int i = 0;i < n;i++){
	score[i] = sc.nextInt();
	}
	double average = 0,variance = 0;
	for(int i = 0;i < n;i++){
	average = average+score[i];
	}
	average = average/n;
	for(int i = 0;i < n;i++){
	variance = (score[i]-average)*(score[i]-average)+variance;
	}
	variance = variance/n;
	System.out.println(Math.sqrt(variance));
     }   
   }
  }
}
