#include <bits/stdc++.h>
using namespace std;
const int NM = 7000, inf = 17;
int N, D, A[NM+5], ans = 0;
vector <int> v;
int f[NM+5][NM+5];
deque <int> dq[NM+5];
void remove(int j, int i){
if (!dq[j].empty() && dq[j].front() == i) dq[j].pop_front();
}
void add(int j, int i){
while (!dq[j].empty() && f[i][j] >= f[dq[j].back()][j]) dq[j].pop_back();
dq[j].push_back(i);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N >> D;
for (int i = 1; i <= N; i++){
cin >> A[i];
v.push_back(A[i]);
}
sort(v.begin(), v.end());
for (int i = 1; i <= N; i++)
A[i] = lower_bound(v.begin(), v.end(), A[i])-v.begin()+1;
for (int i = 0; i <= N; i++)
if (i != A[1]) f[1][i] = -inf; else f[1][i] = 1;
for (int i = 0; i <= N; i++)
dq[i].push_back(1);
for (int i = 2; i <= N; i++){
for (int j = 0; j <= N; j++)
if (j != A[i]) f[i][j] = -inf; else f[i][j] = 1;
for (int j = 0; j <= N; j++){
if (i-D-1 >= 1) remove(j, i-D-1);
if (j < A[i]) f[i][A[i]] = max(f[i][A[i]], f[dq[j].front()][j]+1);
else f[i][j] = max(f[i][j], f[dq[j].front()][j]);
}
for (int j = 0; j <= N; j++)
add(j, i);
}
for (int i = 0; i <= N; i++)
ans = max(ans, f[N][i]);
cout << ans;
return 0;
}
