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

found_num = []
j_list = []

j = 0
while j < N - 1:
    if A[j] in found_num:
        break
    else:
        found_num.append(A[j])
        j_list.append(j + 1)
    j += 1

found_num2 = []

while j < N:
    if A[j] in found_num:
        index = found_num.index(A[j])
        j_list = j_list[index:]
    if A[j] in found_num2:
        j_list = []
        break
    else:
        found_num2.append(A[j])
    j += 1

print(len(j_list))
print(*j_list)