import math
n,k=map(int,input().split())
a=list(map(int,input().split()))
c=[]
for i in range(0,n-k+1):
    s=a[i:i+k]
    t=sum(s)
    b=math.ceil(t/k)
    d=math.floor(t/k)
    e=0
    f=0
    for u in range(0,k):
        e+=abs(b-a[i+u])
        f+=abs(d-a[i+u])
    else:
        if e>f:
            c.append(f)
        else:
            c.append(e)
else:
    print(min(c))