#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define ld long double
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pdd pair<ld, ld>
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second

pii a[500005];
unordered_map<int, int> m;

int main() {
    srand(time(0));
    cin.sync_with_stdio(false);

    int n;
    scanf("%d", &n);

    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i].fi);
        a[i].fi %= n;
        a[i].se = i;
    }

    sort(a + 1, a + n + 1);

    int sum = 0;
    m[0] = 0;
    for (int i = 1; i <= n; i++) {
        int x = a[i].fi;
        sum = (sum + x) % n;

        if (m.count(sum)) {
            int mlc = m[sum];
            printf("%d\n", i - mlc);
            for (int j = mlc + 1; j <= i; j++) {
                printf("%d ", j);
            }
            return 0;
        }

        m[sum] = i;
    }

    for (int c = 1; c <= 3; c++) {
        m.clear();
        int sum = 0;
        m[0] = 0;
        random_shuffle(a + 1, a + n + 1);
        for (int i = 1; i <= n; i++) {
            int x = a[i].fi;
            sum = (sum + x) % n;

            if (m.count(sum)) {
                int mlc = m[sum];
                printf("%d\n", i - mlc);
                for (int j = mlc + 1; j <= i; j++) {
                    printf("%d ", a[j].se);
                }
                return 0;
            }

            m[sum] = i;
        }
    }

    return 0;
}