import java.util.Scanner;

public class Main {

	static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	}

	static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	}

	public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {

	static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	}

	static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	}

	public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	}
} Main static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	} avg {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	} double avg = 0; avg 0 int sum = 0; sum 0 for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		} int i = 0 ; int i = 0 ; i 0 i < num i num i++ i++ i {
			sum += member[i];
		} {
			sum += member[i];
		} sum += member[i] sum member[i] member i avg = (double)sum / (double)num avg (double)sum / (double)num (double)sum (double)num return avg; avg int num num int member[] member static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	} std_dev {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	} double std_dev = 0; std_dev 0 for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		} int i = 0 ; int i = 0 ; i 0 i < num i num i++ i++ i {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		} {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		} std_dev += Math.pow( ( member[i] - avg ), 2 ) std_dev Math.pow( ( member[i] - avg ), 2 ) Math.pow Math ( member[i] - avg ) member[i] member i avg 2 std_dev =  Math.sqrt( std_dev / num ) std_dev Math.sqrt( std_dev / num ) Math.sqrt Math std_dev / num std_dev num return std_dev; std_dev int num num int member[] member double avg avg public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	} main {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	} int student_num = 0; student_num 0 int[] score; score double score_avg = 0; score_avg 0 double std_dev = 0.0; std_dev 0.0 Scanner sc= new Scanner( System.in ); sc new Scanner( System.in ) while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		} true {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		} student_num = sc.nextInt() student_num sc.nextInt() sc.nextInt sc if( student_num == 0) {
				break;
			} student_num == 0 student_num 0 {
				break;
			} break; score = new int[student_num] score new int[student_num] student_num for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			} int i = 0; int i = 0; i 0 i < student_num i student_num i++ i++ i {
				score[i] = sc.nextInt();
			} {
				score[i] = sc.nextInt();
			} score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc score_avg = avg( student_num, score ) score_avg avg( student_num, score ) avg student_num score std_dev = std_dev( student_num, score, score_avg ) std_dev std_dev( student_num, score, score_avg ) std_dev student_num score score_avg System.out.println( std_dev ) System.out.println System.out System System.out std_dev sc.close() sc.close sc String[] args args public class Main {

	static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	}

	static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	}

	public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	}
} public class Main {

	static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	}

	static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	}

	public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	}
} Main
import java.util.Scanner;

public class Main {

	static double avg( int num, int member[] ) {
		double avg = 0;
		int sum = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			sum += member[i];
		}

		avg = (double)sum / (double)num;

		return avg;
	}

	static double std_dev( int num, int member[], double avg ) {
		double std_dev = 0;

		for ( int i = 0 ; i < num ; i++ ) {
			std_dev += Math.pow( ( member[i] - avg ), 2 );
		}

		std_dev =  Math.sqrt( std_dev / num );

		return std_dev;
	}

	public static void main(String[] args) {

		int student_num = 0;
		int[] score;
		double score_avg = 0;
		double std_dev = 0.0;

		Scanner sc= new Scanner( System.in );

		while( true ) {

			student_num = sc.nextInt();

			if( student_num == 0) {
				break;
			}

			score = new int[student_num];

			for ( int i = 0; i < student_num ; i++ ) {
				score[i] = sc.nextInt();
			}

			score_avg = avg( student_num, score );

			std_dev = std_dev( student_num, score, score_avg );

			System.out.println( std_dev );
		}
		sc.close();
	}
}
