/*
  Name:    trip.c
  Purpose: Solution to Programming Challenges "The Trip" (# 10137)
  Author:  Bill Slough
  Date:    January 21, 2012
*/

#include <stdio.h>

#define MAX_STUDENTS 1000

int main() {
    int d, c;               /* dollars and cents */
    int n;                  /* number of students for any one trip */
    int i;                  /* loop index */

    int amt[MAX_STUDENTS];  /* amount each student paid, in cents */
    int total;              /* total amount, in cents, for one trip */

    int average;            /* amount each student should pay for trip,
			       not counting a possible extra cent */
    int leftover;           /* number of cents to distribute among students
			       to make the total exact */

    int toDistribute;       /* amount of money to distribute to share the costs */
  
    scanf("%d", &n); 
    while (n != 0) {
	/* Collect and save the data for the current trip */
	for (i = 0; i < n; i++) {
	    scanf("%d.%d", &d, &c);
	    amt[i] = 100*d + c;
	}

	/* Determine the total amount paid for this trip */
	total = 0;
	for (i = 0; i < n; i++) {
	    total = total + amt[i];
	}

	/* Determine the average amount */
	average = total/n;      /* the FLOOR of the true average */
	leftover = total % n;   

	/* Examine what each student paid; determine the total amount to be repaid. */
	toDistribute = 0;
	for (i = 0; i < n; i++) {
	    if (amt[i] > average) {
		/* this student overpaid and needs reimbursement */
		toDistribute = toDistribute + (amt[i] - average);

		/* To keep reimbursements lower, increase the cost
		   of the overpayers by one penny */
		if (leftover > 0) {
		    toDistribute = toDistribute - 1;
		    leftover = leftover - 1;
		}
	    }
	}

	/* Announce the minimum amount which needs to be redistributed */
	printf("$%d.%02d\n", toDistribute/100, toDistribute % 100);
    
	/* Get ready for the next group... */
	scanf("%d", &n);
    }

    return 0;
}