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

found_num_l = dict()

# left = -1
right = N - 1
i = 0
while i < N:
    if A[i] in found_num_l:
        # left = found_num_l[A[i]]
        right = i
        break
    else:
        found_num_l[A[i]] = i
    i += 1

found_num_r = dict()
j = N - 1
# right = N
left = 0
while j >= 0:
    if A[j] in found_num_r:
        # right = found_num_r[A[j]]
        left = j
        break
    else:
        found_num_r[A[j]] = j
    j -= 1

# found_num = {**found_num_l, **found_num_r}
if left >= right:
    j_list = []
else:
    j_list = list(range(left + 1, right + 1))
j_list = list(range(left + 1, right + 1))
print(len(j_list))
print(*j_list)