#include <bits/stdc++.h>
using namespace std;
const int MAXH = 500000;
vector<int> P[1 + MAXH];
int main()
{
int k, n;
cin >> n >> k;
for (int i = 0; i < n; ++i) {
int h;
cin >> h;
P[h].push_back(i);
}
int b = 0;
for (int h = 1; h <= MAXH; ++h) {
for (int i = 0, j = 0; j < (int)P[h].size(); ++j) {
int a = P[h][j] - P[h][i] + 1;
int c = j - i + 1;
while (a - c > k) {
++i;
a = P[h][j] - P[h][i] + 1;
c = j - i + 1;
}
b = max(b, c);
}
}
cout << b << endl;
return 0;
}
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