casquinha.cpp

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, s, j;
    cin >> n >> s;
    vector<int> u(s+1);
    int d = 0, ans = 0;
    for (int i = 1; i <= n; i++) {
        cin >> j;
        if (u[j] >= (i - d)) {
            d -= (u[j] - (i - d) + 1);
        }
        d++;
        u[j] = i;
        ans = max(ans, d);
    }
    cout << ans << "\n";
}