import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);
        while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

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

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        }
    }
} Main public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);
        while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        }
    } main {
        Scanner stdIn = new Scanner(System.in);
        while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        }
    } Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        } true {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        } int n = stdIn.nextInt(); n stdIn.nextInt() stdIn.nextInt stdIn if(n == 0) break; n == 0 n 0 break; int[] scores = new int[n]; scores new int[n] n double ave_sum = 0; ave_sum 0 for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            } int i = 0; int i = 0; i 0 i < scores.length i scores.length scores scores.length i++ i++ i {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            } {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            } scores[i] = stdIn.nextInt() scores[i] scores i stdIn.nextInt() stdIn.nextInt stdIn ave_sum += scores[i] ave_sum scores[i] scores i double average = ave_sum / scores.length; average ave_sum / scores.length ave_sum scores.length scores scores.length double variance = 0; variance 0 for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            } int i = 0; int i = 0; i 0 i < scores.length i scores.length scores scores.length i++ i++ i {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            } {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            } variance += ((scores[i] - average) * (scores[i] - average)) / scores.length variance ((scores[i] - average) * (scores[i] - average)) / scores.length ((scores[i] - average) * (scores[i] - average)) (scores[i] - average) scores[i] scores i average (scores[i] - average) scores[i] scores i average scores.length scores scores.length 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) {
        Scanner stdIn = new Scanner(System.in);
        while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

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

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);
        while(true) {
            int n = stdIn.nextInt();
            if(n == 0) break;
            int[] scores = new int[n];
            double ave_sum = 0;
            
            for(int i = 0; i < scores.length; i++) {
                scores[i] = stdIn.nextInt();
                ave_sum += scores[i];
            }
            double average = ave_sum / scores.length;
            double variance = 0;

            for(int i = 0; i < scores.length; i++) {
                variance += ((scores[i] - average) * (scores[i] - average)) / scores.length;
            }

            System.out.println(Math.sqrt(variance));
        }
    }
}

