#include<set>
#include<map>
#include<queue>
#include<stack>
#include<cmath>
#include<vector>
#include<cstdio>
#include<bitset>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
using namespace std;
ll ans;
int n,k;
int s[100010];
struct treap
{treap *ls,*rs;int size;int val;int rnd;ll sum;treap(){}treap(treap *son,int v){ls=rs=son;size=1;val=v;sum=1ll*v;rnd=rand();}void pushup(){sum=ls->sum+rs->sum+val;size=ls->size+rs->size+1;}
}tr[100010],nil;
typedef treap* node;
node root,null,cnt;
node a,b,c;
inline void init()
{nil=treap(NULL,0);null=&nil;null->ls=null->rs=null;null->size=0;root=null;cnt=tr;
}
inline node build(int v)
{*cnt=treap(null,v);return cnt++;
}
inline node merge(node x,node y)
{if(x==null){return y;}if(y==null){return x;}if(x->rnd<y->rnd){x->rs=merge(x->rs,y);x->pushup();return x;}else{y->ls=merge(x,y->ls);y->pushup();return y;}
}
inline void split1(node rt,node &x,node &y,int k)
{if(rt==null){x=y=null;return ;}if(rt->ls->size>=k){y=rt;split1(rt->ls,x,y->ls,k);}else{x=rt;split1(rt->rs,x->rs,y,k-1-rt->ls->size);}rt->pushup();
}
inline void split2(node rt,node &x,node &y,int k)
{if(rt==null){x=y=null;return ;}if(rt->val>=k){y=rt;split2(rt->ls,x,y->ls,k);}else{x=rt;split2(rt->rs,x->rs,y,k);}rt->pushup();
}
inline void query()
{split1(root,a,b,k/2);split1(b,b,c,1);ll res=1ll*a->size*b->val-a->sum;res+=c->sum-1ll*c->size*b->val;ans=min(res,ans);root=merge(merge(a,b),c);
}
int main()
{srand(12378);scanf("%d%d",&n,&k);ans=1ll<<60;init();for(int i=1;i<=n;i++){scanf("%d",&s[i]);}for(int i=1;i<=k;i++){split2(root,a,b,s[i]);root=merge(merge(a,build(s[i])),b);}query();for(int i=k+1;i<=n;i++){split2(root,a,b,s[i-k]);split1(b,b,c,1);root=merge(a,c);split2(root,a,b,s[i]);root=merge(merge(a,build(s[i])),b);query();}printf("%lld",ans);
}