#include "bits/stdc++.h"

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

using LL = long long int;
using LD = long double;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vb>;

const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

const int dy[] = { 0, 1, 0, -1 };
const int dx[] = { 1, 0, -1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
LL gcd(LL x, LL y) { return y ? gcd(y, x % y) : x; }

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

	int n, m;
	cin >> n >> m;

	vi d(m);
	for (int i = 0; i < m; i++) {
		cin >> d[i];
	}
	SORT(d);

	int ans = INF;
	for (int i = 0; i < m; i++) {
		for (int j = i + n - 1; j < m; j++) {
			int leftVal = abs(min(0, d[i]));
			int rightVal = abs(max(0, d[j]));
			int val = min(2 * leftVal + rightVal, 2 * rightVal + leftVal);
			ans = min(ans, val);
		}
	}

	cout << ans << endl;
	return 0;
}