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

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

ans = []
for i in range(L+1, R+1):
    ans.append(i)

if [L, R] == [-1, N]:
    print(N-1)
    print(*list(range(1, N)))
else:
    print(len(ans))
    print(*ans)