#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  int ans = 0;
  set<int> st;
  int r = 0;
  rep(l, n) {
    while (r < n && !st.contains(a[r])) st.insert(a[r++]);
    ans = max(ans, r - l);
    assert(st.contains(a[l]));
    st.erase(a[l]);
  }
  cout << ans << '\n';
  return 0;
}