#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[boxes.size() / 2];
	if (boxes.size() % 2 == 0) median = boxes[(boxes.size() - 1) / 2];

	long long count = 0;
	for (size_t j = 0; j < boxes.size(); j++) {
		if (boxes[j] > median) {
			count += boxes[j] - median;
		} else if (boxes[j] < median) {
			count += median - boxes[j];
		}
	}

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