#include <iostream>

using namespace std;

const int N = 100010;

int main() {
  bool flag[N];
  int nums[N];
  int n, res = 0;

  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> nums[i];
  }

  int tmp = 0, i = 0, j = 0;

  for (; j < n; j++) {
    if (!flag[nums[j]]) {
      flag[nums[j]] = true;
      continue;
    } else {
      int span = 1;
      tmp = j - i;
      for (; nums[i] != nums[j]; i++) {
        flag[nums[i]] = false;
        span++;
      }
      i++;
      res = max(res, tmp);
      tmp = tmp - span;
    }
  }

  tmp = j - i;
  res = max(res, tmp);


  cout << res << endl;
}