#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;
int main()
{
	int n;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; ++i) cin >> a[i];
	map<int, vector<int>> mp;
	for (int i = 0; i < n; ++i) mp[a[i]].push_back(i);
	for (auto v : mp)
	{
		if (v.second.size() > 2)
		{
			cout << "0\n" << endl;
			return 0;
		}
	}
	int mal = 0, mir = n - 1;
	for (auto v : mp)
	{
		if (v.second.size() == 1) continue;
		mal = max(mal, v.second[0]);
		mir = min(mir, v.second[1]);
	}
	cout << max(mir - mal, 0) << endl;
	for (int i = mal; i < mir; ++i) cout << i + 1 << ' ';
	cout << endl;
}