#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 1000;

int D[MAX_N];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    vector<int> L, R;
    L.emplace_back(0);
    R.emplace_back(0);
    for (int i = 0; i < m; i++) {
        cin >> D[i];
        if (D[i] < 0) L.emplace_back(-D[i]);
        else R.emplace_back(D[i]);
    }
    sort(L.begin(), L.end());
    sort(R.begin(), R.end());
    int l = L.size(), r = R.size();
    vector<int> dp(l);
    int ans = 100000000;
    for (int i = max(n - r + 1, 0), e = min(l, n + 1); i < e; i++) {
        dp[i] = min(L[i] * 2 + R[n - i], L[i] + R[n - i] * 2);
        ans = min(ans, dp[i]);
    }
    cout << ans << "\n";
    return 0;
}