#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    vector<int> t(n);
    for (int& x : t)
        cin >> x;

    vector<int> diff(n);
    diff[0] = t[0];
    for (int i = 1; i < n; i++)
        diff[i] = t[i] - t[i - 1];

    sort(diff.begin(), diff.end());

    vector<int> ans = { 1 };

    for (int i = 1; i < n; i++)
        if (i == n - 1 || diff[i + 1] != diff[i])
            ans.push_back(i + 2);

    cout << ans.size() << "\n";
    for (int const& x : ans)
        cout << x << " ";
    cout << "\n";
}