#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;


int main() {

	int n, m;
	cin >> n >> m;
	int s = 0;
	vector<int>a, b;
	for (int i = 0; i < m; i++) {
		int x;
		cin >> x;
		if (x > 0)a.push_back(x);
		if (x < 0)b.push_back(x);
		if (!x)s++;
	}
	if (s == n) {
		cout << 0 << endl; return 0;
	}
	sort(a.begin(), a.end());
	sort(b.begin(), b.end());
	reverse(b.begin(), b.end());
	int t = 99999999;
	for (int i = b.size() - 1; i >= 0; i--) {
		int x = 0; int w = i + 1;
		if (i + s +1> n)continue;
		x += abs(b[i]);
		//cout << x << endl;
		if (w + s < n) {
			x *= 2;
			int r = n - s - w;
			x += a[r - 1];
		}
		t = min(t, x);

	}
	//cout << t;
	if (a.size() > n - s)t = min(t, a[n - s - 1]);
	cout << t << endl;

	return 0;


}