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

int main(void){
  int n, m;
  cin >> n >> m;
  long long d[m];
  for(int i = 0; i < m; i++) cin >> d[i];
  sort(d, d + m);
  long long ans = 1e+18;
  for(int i = 0; i < m - n; i++){
    long long temp;
    temp = abs(d[i]) + abs(d[i] - d[i + n - 1]);
    temp = min(temp, abs(d[i + n - 1]) + abs(d[i] - d[i + n - 1]));
    ans = min(ans, temp);
  }
  cout << ans << endl;
  return 0;
}