#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <cstdlib>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional> 
#include <iomanip>
#include <unordered_map>
#include <memory.h>
#include <unordered_set>
#include <fstream>

using namespace std;

int main(void)
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N, M, t;
	vector <int> v;

	cin >> N >> M;
	for (int i = 0; i < M; i++)
	{
		cin >> t;
		v.push_back(t);
	}

	sort(v.begin(), v.end());

	int res = 1e9;

	for (int i = 0; i <= M - N; i++)
	{
		int l = i;
		int r = i + N - 1;
		if (v[l] < 0 && v[r] < 0)
		{
			res = min(res, abs(v[l]));
		}
		else if(v[l] >= 0 && v[r]>=0)
		{
			res = min(res, abs(v[r]));
		}
		else
		{
			int x = 2 * abs(v[l]) + abs(v[r]);
			int y = abs(v[l]) + 2 * abs(v[r]);
			res = min(res, min(x, y));
		}
	}

	cout << res << '\n';


	return 0;
}