#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;
typedef vector<int> VI;
typedef pair<int, int> PI;
const double EPS=1e-9;

const int N = 100010;


int a[N];


int main(void){
  int n;
  cin >> n;
  REP(i, 0, n) {
    cin >> a[i];
  }
  int q = 1;
  int m = 0;
  set<int> acc;
  REP(p, 0, n) {
    for (; q < n && acc.count(a[q]) == 0; ++q) {
      acc.insert(a[q]);
    }
    m = max(m, q - p);
    acc.erase(a[p]);
  }
  cout << m << endl;
}