n = int(input())
a = list(map(int, input().split()))
ok = [True] * (n + 1)
for _ in range(2):
    now = True
    seen = set()
    for i in range(n):
        if a[i] in seen:
            now = False
        else:
            seen.add(a[i])
        ok[i+1] &= now
    a.reverse()
    ok.reverse()

ans = [j for j in range(1, n) if ok[j]]
print(len(ans))
print(*ans)