#include <bits/stdc++.h>
#define pii pair < int , int >
#define ll long long
#define pipii pair < int , pair < int , int > >
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define pri_que priority_queue 
using namespace std;
const int maxn=3e5+14;
int n , k;
int a[maxn];
void sub12(){
	if (k >= n - 1 ) {
		cout << n;
		return;
	}
	int ans = k + 1;
	int cnt = 0;
	for (int i = 1; i <= n; i++, cnt ++){
		unordered_map < int , int > m;
		int maxtanso = 1;
		
		for (int j = i; j <= n; j ++, cnt++){
			m[a[j]]++;
			maxtanso = max(maxtanso, m[a[j]]);
			if ( j - i + 1 - maxtanso > k) break;
			ans = max(ans, j - i + 1);
		}
	}
	cout << ans << endl ;
}

void sub3(){
	unordered_map < int , vector < pii > > m ;
	unordered_map < int , int > cnt ;
	
	for (int i = 1; i <= n; i++){
		if (cnt[a[i]] == 0){
			m[a[i]].pb(mp(0, 0));
		}
		cnt[a[i]] ++;
		m[a[i]].pb(mp(i, cnt[a[i]]));
	}
	
	int ans = k + 1;
	
	if (k >= n - 1 ) {
		cout << n;
		return ;
	}
	
	unordered_map < int , int > dem ;
	for (int i = 1; i <= n; i++){
		dem[a[i]] ++;
		int l = 1, r = m[a[i]].size();
		int res = 1;
		while (l <= r) {
			int d = (l + r) >> 1;
			if (m[a[i]][d].fi >= i) {
				r = d - 1;
				continue;
	    	}
	    	int maxtanso = dem[a[i]] - m[a[i]][d].se + 1;
			if (i + 1 - maxtanso - k > m[a[i]][d].fi) l = d + 1;
			else {
				res = max(res, min(maxtanso + k , n));
				r = d - 1;
			}
			
		}
		ans = max(ans , res);
	}
	
	cout << ans ;
}
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);    cout.tie(0);
	if (fopen("SEQ.INP","r")){
		freopen("SEQ.INP","r",stdin);
		freopen("SEQ.OUT","w",stdout);
	}
	cin >> n >> k;
	for (int i = 1; i <= n; i++){
		cin >> a[i];
	}
    if (n <= 5000) sub12();
    else sub3();
	return 0;
}