#include <bits/stdc++.h>
using namespace std;

#define DUMP(x) cerr << #x << "=" << x << endl
#define DUMP2(x, y) cerr<<"("<<#x<<", "<<#y<<") = ("<<x<<", "<<y<<")"<< endl
#define BINARY(x) static_cast<bitset<16> >(x)

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)

#define in_range(x, y, w, h) (0<=(int)(x) && (int)(x)<(int)(w) && 0<=(int)(y) && (int)(y)<(int)(h))
#define ALL(a) (a).begin(),(a).end()

typedef long long ll;
const int INF = 1e9;
typedef pair<int, int> PII;
int dx[4]={0, -1, 1, 0}, dy[4]={-1, 0, 0, 1};

int main()
{
    ios::sync_with_stdio(false);

    int N, M;
    cin >> N >> M;
    vector<int> left, right;

    rep(i, M) {
        int D; cin >> D;
        if (D > 0) {
            right.push_back(D);
        } else if (D < 0) {
            left.push_back(-D);
        } else {
            N--;
        }
    }

    sort(ALL(right));
    sort(ALL(left));

    int ans = INF;
    rep(i, 2) {
        for (int j=0; j<=min(N, (int)right.size()); j++) {
            if ((N-j) > left.size()) continue;

            int tmp = 0;
            if (j > 0) tmp += right[j-1];
            if (N-j > 0) tmp += left[N-j-1];
            if (j > 0 && N-j > 0) tmp += right[j-1];

            ans = min(ans, tmp);
        }

        swap(left, right);
    }

    cout << ans << endl;
}