#include <bits/stdc++.h>
using namespace std;
struct IoSetup {
  IoSetup() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} IoSetup;
using Int = __int128_t;
using ll = long long;
using pii = pair<int, int>;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr int SMOD = 1000000007;
constexpr int NMOD = 998244353;
constexpr int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr int dy[] = {0, -1, 0, 1, -1, 1, -1, 1};
inline bool inside(int x, int y, int w, int h) {
  return (x >= 0 && y >= 0 && x < w && y < h);
}
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) return (a = b, 1);
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) return (a = b, 1);
  return 0;
}
template <typename Monoid, typename OperatorMonoid = Monoid>
struct LazySegmentTree {
  using F = function<Monoid(Monoid, Monoid)>;
  using G = function<Monoid(Monoid, OperatorMonoid)>;
  using H = function<OperatorMonoid(OperatorMonoid, OperatorMonoid)>;
  int sz, height;
  vector<Monoid> data;
  vector<OperatorMonoid> lazy;
  const F f;
  const G g;
  const H h;
  const Monoid M1;
  const OperatorMonoid OM0;
  LazySegmentTree(int n, const F f, const G g, const H h, const Monoid &M1,
                  const OperatorMonoid OM0)
      : f(f), g(g), h(h), M1(M1), OM0(OM0) {
    sz = 1;
    height = 0;
    while (sz < n) sz <<= 1, height++;
    data.assign(2 * sz, M1);
    lazy.assign(2 * sz, OM0);
  }
  void set(int k, const Monoid &x) { data[k + sz] = x; }
  void build() {
    for (int k = sz - 1; k > 0; k--) {
      data[k] = f(data[2 * k + 0], data[2 * k + 1]);
    }
  }
  inline void propagate(int k) {
    if (lazy[k] != OM0) {
      lazy[2 * k + 0] = h(lazy[2 * k + 0], lazy[k]);
      lazy[2 * k + 1] = h(lazy[2 * k + 1], lazy[k]);
      data[k] = reflect(k);
      lazy[k] = OM0;
    }
  }
  inline Monoid reflect(int k) {
    return lazy[k] == OM0 ? data[k] : g(data[k], lazy[k]);
  }
  inline void recalc(int k) {
    while (k >>= 1) data[k] = f(reflect(2 * k + 0), reflect(2 * k + 1));
  }
  inline void thrust(int k) {
    for (int i = height; i > 0; i--) propagate(k >> i);
  }
  void update(int a, int b, const OperatorMonoid &x) {
    thrust(a += sz);
    thrust(b += sz - 1);
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1) lazy[l] = h(lazy[l], x), ++l;
      if (r & 1) --r, lazy[r] = h(lazy[r], x);
    }
    recalc(a);
    recalc(b);
  }
  Monoid query(int a, int b) {
    thrust(a += sz);
    thrust(b += sz - 1);
    Monoid L = M1, R = M1;
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1) L = f(L, reflect(l++));
      if (r & 1) R = f(reflect(--r), R);
    }
    return f(L, R);
  }
  Monoid operator[](const int &k) { return query(k, k + 1); }
  template <typename C>
  int find_subtree(int a, const C &check, Monoid &M, bool type) {
    while (a < sz) {
      propagate(a);
      Monoid nxt =
          type ? f(reflect(2 * a + type), M) : f(M, reflect(2 * a + type));
      if (check(nxt))
        a = 2 * a + type;
      else
        M = nxt, a = 2 * a + 1 - type;
    }
    return a - sz;
  }
  template <typename C>
  int find_first(int a, const C &check) {
    Monoid L = M1;
    if (a <= 0) {
      if (check(f(L, reflect(1)))) return find_subtree(1, check, L, false);
      return -1;
    }
    thrust(a + sz);
    int b = sz;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1) {
        Monoid nxt = f(L, reflect(a));
        if (check(nxt)) return find_subtree(a, check, L, false);
        L = nxt;
        ++a;
      }
    }
    return -1;
  }
  template <typename C>
  int find_last(int b, const C &check) {
    Monoid R = M1;
    if (b >= sz) {
      if (check(f(reflect(1), R))) return find_subtree(1, check, R, true);
      return -1;
    }
    thrust(b + sz - 1);
    int a = sz;
    for (b += sz; a < b; a >>= 1, b >>= 1) {
      if (b & 1) {
        Monoid nxt = f(reflect(--b), R);
        if (check(nxt)) return find_subtree(b, check, R, true);
        R = nxt;
      }
    }
    return -1;
  }
};
signed main() {
  int n, k;
  cin >> n >> k;
  vector<int> a(n);
  using X = int;
  using M = int;
  LazySegmentTree<X, M> seg(
      n, [](X a, X b) { return max(a, b); }, [](X a, M b) { return a + b; },
      [](M a, M b) { return a + b; }, -INT_MAX, 0);
  for (int i = 0; i < n; i++) seg.set(i, 0);
  seg.build();
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    seg.update(max(0, i - k), min(n, i + k + 1), 1);
  }
  int mv = 1;
  for (int i = 0; i < n; i++) {
    chmax(mv, seg[i]);
  }
  cout << mv << endl;
  return 0;
}
