#include <iostream>
#include <algorithm>
using namespace std;

int n, m;
int d[1000];

int main() {
	int i, j;
	int ans = 1145141919;
	
	cin >> n >> m;
	for (i = 0; i < m; i++) { cin >> d[i]; }
	sort(d, d + m);
	
	for (i = 0; i < m; i++) {
		for (j = i + n - 1; j < m; j++) {
			//d[i]～d[j]をひろう
			int x = d[i] < 0 ? -d[i] : 0;
			int y = d[j] > 0 ? d[j] : 0;
			//位置[x, y]を移動する
			int dist = min(x + 2 * y, 2 * x + y);
			ans = min(ans, dist);
		}
	}
	cout << ans << endl;
	return 0;
}