n,k=map(int,input().split())
a=list(map(int,input().split()))
inf=float('inf')
ans=inf
# 右端に-1を固める
tmp0=0
tmp1=0
for x in a:
  if a[k]-x>0:
    tmp1+=a[k]-x
  else:
    tmp0+=x-a[k]
ans=min(ans,tmp1-tmp0)
for i in reversed(range(k)):
  tmp0+=(n-k)*(a[i+1]-a[i])
  tmp1-=(i+1)*(a[i+1]-a[i])
  tmp1+=(k-i-1)*(a[i+1]-a[i])
  ans=min(ans,tmp1-tmp0)

# 左端に-1を固める。
a=[-x for x in a]
a.reverse()
tmp0=0
tmp1=0
for x in a:
  if a[k]-x>0:
    tmp1+=a[k]-x
  else:
    tmp0+=x-a[k]
ans=min(ans,tmp1-tmp0)
for i in reversed(range(k)):
  tmp0+=(n-k)*(a[i+1]-a[i])
  tmp1-=(i+1)*(a[i+1]-a[i])
  tmp1+=(k-i-1)*(a[i+1]-a[i])
  ans=min(ans,tmp1-tmp0)

print(ans)