#include<iostream>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<utility>

#define ll long long
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
using namespace std;

void Fast_IO(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
    #endif
}






void solve(){

ll n,k,pos; cin>>n>>k;
ll arr[n];
ll path =0;
for(int i=0; i<n; i++){
    cin>>arr[i];
    if(i>0){
        if(arr[i]>=0 && arr[i-1]<0) pos =i;
    }
}
if(arr[0]>=0){
    if(arr[0]==0) k-=1;
    for(int i=0; i<n; i++){
        path=abs(arr[i]);
        k--;
        if(k==0) break;
    }
}else if(arr[n-1]<=0){
    if(arr[n-1]==0) k-=1;
    for(int i=n-1; i>0; i--){
        path = abs(arr[i]);
        k--;
        if(k==0) break;
    }
}else{
    int left=pos-1, right = pos;
    if(arr[pos]==0){
        k--;
        right = pos+1;
    }
    ll right_path=0,left_path=0;
for(; k>0;){
    if(arr[right]<=abs(arr[left])){
        k--;
        right_path = arr[right];
        right++;
    }else if(arr[right]>abs(arr[left])){
        k--;
        left_path = abs(arr[left]);
        left--;
    }
}
// cout<<left_path<<' '<<right_path<<' '<<pos<<' ';
path = 2*min(left_path,right_path)+max(right_path,left_path);
}

cout<<path;

}

int main(){
    Fast_IO();
int t =1;
//cin>>t;
while(t--){
solve();
}
return 0;
}