def main():
    N = int(input())
    A = list(map(int, input().split()))

    left = [True]

    s = set()
    isok = True

    for i in range(N):
        if A[i] in s:
            isok = False

        s.add(A[i])
        left.append(isok)

    A = A[::-1]

    right = [True]

    s = set()
    isok = True

    for i in range(N):
        if A[i] in s:
            isok = False

        s.add(A[i])
        right.append(isok)

    right = right[::-1]
    ans = []

    # print(*left)
    # print(*right)

    for i in range(1, N):
        if left[i] and right[i]:
            ans.append(i)

    print(len(ans))
    print(*ans)
    return 0


main()