#include <iostream>
#include <iomanip>
#include <algorithm>
#include <complex>
#include <utility>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <tuple>
#include <cmath>
#include <bitset>
#include <cctype>
#include <set>
#include <map>
#include <unordered_map>
#include <numeric>
#include <functional>
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define PRINT(V) cout << V << "\n"
#define SORT(V) sort((V).begin(),(V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
inline void Yes(bool condition){ if(condition) PRINT("Yes"); else PRINT("No"); }
template<class itr> void cins(itr first,itr last){
    for (auto i = first;i != last;i++){
        cin >> (*i);
    }
}
template<class itr> void array_output(itr start,itr goal){
    string ans = "",k = " ";
    for (auto i = start;i != goal;i++) ans += to_string(*i)+k;
    if (!ans.empty()) ans.pop_back();
    PRINT(ans);
}
ll gcd(ll a, ll b) {
    return a ? gcd(b%a,a) : b;
}
const ll INF = 1e15;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
typedef pair<ll,ll> P;
typedef pair<double,double> point;
const ll MAX = 2000005;
constexpr ll nx[8] = {1,0,-1,0,1,-1,1,-1};
constexpr ll ny[8] = {0,1,0,-1,1,1,-1,-1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll h,w;
    cin >> h >> w;
    vector<string> grid(h+2);
    string s = "";
    rep(i,w+2) s += '.';
    grid[0] = s;
    grid[h+1] = s;
    rep(i,h){
        cin >> grid[i+1];
        grid[i+1] = '.'+grid[i+1]+'.';
    }
    rep(i,1,h+1){
        rep(j,1,w+1){
            bool out = 1;
            if (grid[i][j] == '#'){
                rep(k,4){
                    ll xn = i+nx[k];
                    ll yn = j+ny[k];
                    if (grid[xn][yn] == '#') out = 0; 
                }
                if (out){
                    PRINT("No");
                    return 0;
                }
            }
        }
    }
    PRINT("Yes");
}

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long
int main(){
  ll n,k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i,n){
    cin >> a.at(i);
  }
  ll i,sum=0,mini=1e9+7;
  for(i=0;i<=n-k;i++){
    sum=a.at(i+k-1)-a.at(i);
    if(a.at(i+k-1)>0 && a.at(i)<0){
      ll p=min(a.at(i+k-1),abs(a.at(i)));
      sum+=p;
    }else{
      sum=max(abs(a.at(i+k-1)),abs(a.at(i)));
    }
    mini=min(mini,sum);
  }
  cout << mini;
}