import java.util.*;
 
public class Main {
    public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	}
} import java.util.*; util.* java public class Main {
    public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	}
} Main public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	} main {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	} Scanner scan = new Scanner( System.in ); scan new Scanner( System.in ) while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		} true {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		} int studentNum = scan.nextInt(); studentNum scan.nextInt() scan.nextInt scan if ( studentNum == 0 ) {
				break;
			} studentNum == 0 studentNum 0 {
				break;
			} break; int[] point = new int[studentNum]; point new int[studentNum] studentNum int sum = 0; sum 0 for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			} int i = 0; int i = 0; i 0 i < studentNum i studentNum i++ i++ i {
				point[i] = scan.nextInt();
				sum += point[i];
				
			} {
				point[i] = scan.nextInt();
				sum += point[i];
				
			} point[i] = scan.nextInt() point[i] point i scan.nextInt() scan.nextInt scan sum += point[i] sum point[i] point i double average = (double)sum / (double)studentNum; average (double)sum / (double)studentNum (double)sum (double)studentNum double variance = 0; variance 0 for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			} int i = 0; int i = 0; i 0 i < studentNum i studentNum i++ i++ i {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			} {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			} double deviation	=	point[i]	- average; deviation point[i]	- average point[i] point i average variance			+=	deviation	* deviation variance deviation	* deviation deviation deviation variance = variance / studentNum variance variance / studentNum variance studentNum double standardDeviation = Math.sqrt( variance ); standardDeviation Math.sqrt( variance ) Math.sqrt Math variance System.out.println( standardDeviation ) System.out.println System.out System System.out standardDeviation String args[] args public class Main {
    public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	}
} public class Main {
    public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	}
} Main
import java.util.*;
 
public class Main {
    public static void main( String args[] ) {
        Scanner scan = new Scanner( System.in );
		
		while( true ) {
			int studentNum = scan.nextInt();
			
			if ( studentNum == 0 ) {
				break;
			}

			int[] point = new int[studentNum];
			
			// input, calculate sum
			int sum = 0;
			for( int i = 0; i < studentNum; i++ ) {
				point[i] = scan.nextInt();
				sum += point[i];
				
			}
			
			// calculate average
			double average = (double)sum / (double)studentNum;
			
			// calculate variance
			double variance = 0;
			for( int i = 0; i < studentNum; i++ ) {
				double deviation	=	point[i]	- average;
				variance			+=	deviation	* deviation;

			}
			variance = variance / studentNum;
			
			// calculate standardDeviation
			double standardDeviation = Math.sqrt( variance );
			
			System.out.println( standardDeviation );
		}
		
	}
}