#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 = std::min(boxes[box_num / 2], (std::accumulate(boxes.begin(), boxes.end(), 0LL) + having_candy_num) / box_num);

	long long count = 0;
	long long h = having_candy_num;
	for (size_t j = 0; j < boxes.size(); j++) {
		count += abs(boxes[j] - median);
	}

	std::cout << count << std::endl;
	return 0;
}