#include<bits/stdc++.h> using namespace std; int main(){ int i,j,k,l; int m,n; int h,x,y; cin>>n>>m; vector<int> v; l=0; for (i=0;i<m;i++){ cin>>j; v.push_back(j); } sort(v.begin(),v.end()); int min=-1; for (i=0;i<m-n+1;i++){ l=v[i]; h=v[i+n-1]; if (0<=l){ k=h; }else if(0<h){ int t,u; t=(abs(l)*2+h); u=(abs(l)+h*2); k=t>u?u:t; }else { k=abs(l); } //cout<<k<<endl; if (min<0||k<min) min=k; } cout<<min<<endl; return 0; }