#include<iostream>
#include<vector>
#include<algorithm>
#include<numeric>
#include<cmath>

int main() {
	int box_num, having_candy_num;
	std::cin >> having_candy_num >> box_num;

	std::vector<long long> boxes(box_num);
	for (int i = 0; i < box_num; i++) std::cin >> boxes[i];

	std::sort(boxes.begin(), boxes.end());

	long long median = boxes.size() / 2;

	long long count = 0;
	for (int i = median; i >= 0; i--) {
		long long h = having_candy_num;
		for (size_t j = 0; j < boxes.size(); j++) {
			if (boxes[j] > boxes[i]) {
				count += boxes[j] - boxes[i];
				h += boxes[j] - boxes[i];
			} else if (boxes[j] < boxes[i]) {
				count += boxes[i] - boxes[j];
				h -= boxes[i] - boxes[j];
			}
		}
		if (h >= 0)break;
		count = 0;
	}
	std::cout << count << std::endl;
	return 0;
}