#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <cstdio>using namespace std;const int MaxN = 100000 + 5, MaxNode = 100000 * 20 + 15, MN = 1000000 + 5;typedef long long LL;int n, k, Index, Root;
int A[MaxN], T[MaxNode], Son[MaxNode][2];const LL INF = 999999999999;LL Ans;
LL Sum[MaxNode];inline LL gmin(LL a, LL b) {return a < b ? a : b;}inline void Read(int &Num)
{char c; c = getchar();while (c < '0' || c > '9') c = getchar();Num = c - '0'; c = getchar();while (c >= '0' && c <= '9') {Num = Num * 10 + c - '0';c = getchar();}
}void Add(int &x, int s, int t, int Pos, int Num)
{if (x == 0) x = ++Index;T[x] += Num;Sum[x] += (LL)Pos * (LL)Num;if (s == t) return;int m = (s + t) >> 1;if (Pos <= m) Add(Son[x][0], s, m, Pos, Num);else Add(Son[x][1], m + 1, t, Pos, Num);
}int Kth(int x, int s, int t, int k)
{if (s == t) return s;int ret, m = (s + t) >> 1;if (T[Son[x][0]] >= k) ret = Kth(Son[x][0], s, m, k);else ret = Kth(Son[x][1], m + 1, t, k - T[Son[x][0]]);return ret;
}LL GetSum(int x, int s, int t, int l, int r)
{if (l <= s && r >= t) return Sum[x];int m = (s + t) >> 1;LL ret = 0ll;if (l <= m && Son[x][0]) ret += GetSum(Son[x][0], s, m, l, r);if (r >= m + 1 && Son[x][1]) ret += GetSum(Son[x][1], m + 1, t, l, r);return ret;
}int GetNum(int x, int s, int t, int l, int r)
{if (l <= s && r >= t) return T[x];int m = (s + t) >> 1;int ret = 0;if (l <= m && Son[x][0]) ret += GetNum(Son[x][0], s, m, l, r);if (r >= m + 1 && Son[x][1]) ret += GetNum(Son[x][1], m + 1, t, l, r);return ret;
}int main()
{scanf("%d%d", &n, &k);for (int i = 1; i <= n; ++i) Read(A[i]);Root = Index = 0;A[0] = 0;for (int i = 0; i <= k - 1; ++i) Add(Root, 0, MN, A[i], 1);Ans = INF;int t = k / 2 + 1, Temp;LL Now;for (int i = k; i <= n; ++i) {Add(Root, 0, MN, A[i - k], -1);Add(Root, 0, MN, A[i], 1);Temp = Kth(Root, 0, MN, t);Now = (LL)GetNum(Root, 0, MN, 0, Temp - 1) * (LL)Temp - GetSum(Root, 0, MN, 0, Temp - 1);Now += GetSum(Root, 0, MN, Temp + 1, MN) - (LL)GetNum(Root, 0, MN, Temp + 1, MN) * (LL)Temp;Ans = gmin(Ans, Now);}printf("%lld\n", Ans);return 0;
}