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

int abs(int a){
	return 0 <= a ? a : -a;
}

int main(){
	int n, m;
	cin >> n >> m;
	vector<int> l, r;
	while(m--){
		int d;
		cin >> d;
		(d < 0 ? l : r).emplace_back(abs(d));
	}
	l.emplace_back(0);
	r.emplace_back(0);
	sort(l.begin(), l.end());
	sort(r.begin(), r.end());
	int ans = 1 << 30;
	for(int i = 0; i < l.size(); i++) if(n - i < r.size()){
		int dist = min(2 * l[i] + r[n - i], l[i] + 2 * r[n - i]);
		ans = min(ans, dist);
	}
	cout << ans << endl;
}