/* -*- coding: utf-8 -*-
 *
 * 2779.cc:  No.2779 Don't make Pair - yukicoder
 */

#include<cstdio>
#include<vector>
#include<map>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

typedef vector<int> vi;
typedef map<int,vi> mivi;

/* global variables */

int as[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", as + i);

  mivi avs;
  for (int i = 0; i < n; i++) avs[as[i]].push_back(i);

  int l = 0, r = n - 1;
  for (auto &[a, v]: avs) {
    if (v.size() > 2) { puts("0\n"); return 0; }
    if (v.size() == 2) {
      l = max(l, v[0]);
      r = min(r, v[1]);
    }
  }

  int k = max(0, r - l);
  printf("%d\n", k);
  for (int i = l; i < r; i++) printf("%d ", i + 1);
  putchar('\n');

  return 0;
}