#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <set>
#include <map>
#include <numeric>
#include <regex>
#include <tuple>
#include <iomanip>
#include <cmath>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
#define MOD 1000000007 // 10^9 + 7
#define INF 1000000000 // 10^9
#define LLINF 1LL<<60

int a[1009];
int b[1009];

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

	int N, M; cin >> N >> M;

	int num1 = 0, num2 = 0;

	for (int i = 0; i < M; i++){
		int tmp; cin >> tmp;
		if (tmp >= 0) {
			a[num1+1] = tmp;
			num1++;
		}
		else {
			b[num2+1] = -tmp;
			num2++;
		}
	}

	sort(a + 1, a + num1 + 1);
	sort(b + 1, b + num2 + 1);
	a[0] = b[0] = 0;

	int ans = INF;
	
	for (int i = 0; i <= N; i++) {
		if (i <= num1 && N - i <= num2) {
			int d = min(a[i], b[N - i]) + a[i] + b[N - i];
			ans = min(ans, d);
		}
	}

	cout << ans << endl;

	return 0;
}