#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int m, n;
    cin >> m >> n;
    int a[n] = {};
    rep(i,n) cin >> a[i];
    sort(a,a+n);
    int ans = 1001001001;
    rep(i,n-m+1){
        int tmp = abs(a[i]) + abs(a[i+m-1] - a[i]);
        ans = min(ans, tmp);
    }
    srep(i,m-1,n){
        int tmp = abs(a[i]) + abs(a[i] - a[i-(m-1)]);
        ans = min(ans, tmp);
    }
    cout << ans << endl;
    return 0;
}