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

L, R = -1, -1
S = set()
for i in range(N):
    if A[i] in S:
        break
    S.add(A[i])
    L = i
    
S = set()
for i in range(N-1, -1, -1):
    if A[i] in S:
        break
    S.add(A[i])
    R = i

if R == 0:
    R += 1
if L == N - 1:
    L -= 1
ans = list(range(R, L + 2))
print(len(ans))
print(*ans)