class Cumsum:
    def __init__(self,lst,mod=0):
        self.N=len(lst)
        self.mod=mod
        self.cumsum=[0]*(self.N+1)
        self.cumsum[0]=0
        for i in range(1,self.N+1):
            self.cumsum[i]=self.cumsum[i-1]+lst[i-1]
            if self.mod:
                self.cumsum[i]%=self.mod

    def __getitem__(self,i):
        if type(i)==int:
            if 0<=i<self.N:
                a,b=i,i+1
            elif -self.N<=i<0:
                a,b=i+self.N,i+self.N+1
            else:
                raise IndexError('list index out of range')
        else:
            a,b=i.start,i.stop
            if a==None or a<-self.N:
                a=0
            elif self.N<=a:
                a=self.N
            elif a<0:
                a+=self.N
            if b==None or self.N<=b:
                b=self.N
            elif b<-self.N:
                b=0
            elif b<0:
                b+=self.N
        s=self.cumsum[b]-self.cumsum[a]
        if self.mod:
            s%=self.mod
        return s

    def __setitem__(self,i,x):
        if -self.N<=i<0:
            i+=self.N
        elif not 0<=i<self.N:
            raise IndexError('list index out of range')
        self.cumsum[i+1]=self.cumsum[i]+x
        if self.mod:
            self.cumsum[i+1]%=self.mod

    def __len__(self):
        return self.N

    def __str__(self):
        lst=[self.cumsum[i+1]-self.cumsum[i] for i in range(self.N)]
        if self.mod:
            for i in range(self.N):
                lst[i]%=self.mod
        return "["+", ".join(map(str,lst))+"]"

def Bisect_Int(ok,ng,is_ok):
    while abs(ok-ng)>1:
        mid=(ok+ng)//2
        if is_ok(mid):
            ok=mid
        else:
            ng=mid
    return ok

N,K=map(int,input().split())
A=Cumsum(list(map(int,input().split())))
inf=1<<60
ans=inf
for l in range(N-K+1):
    r=l+K
    c0=l
    c1=N-r
    m=l+r-N//2
    for i in (m-2,m-1,m,m+1,m+2,l,r-1):
        def f(l,r):
            return A[l:r]-(r-l)*A[i]
        if 0<=i<N:
            ans=min(ans,f(0,l)-f(l,i)+f(i+1,r)-f(r,N))
print(ans)