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

poses = {}

# 閉区間
flag = False
for i in range(N):
	if A[i] in poses:
		if poses[A[i]][1] == -1:
			poses[A[i]][1] = i
		else:
			flag = True
			break
	else:
		poses[A[i]] = [i+1, -1]

if flag:
	print(0)
	print()
else:
	r = [1, N-1]
	for pos in poses.values():
		if pos[1] == -1: continue
		r[0] = max(r[0], pos[0])
		r[1] = min(r[1], pos[1])
	ans = range(r[0], r[1]+1)
	print(len(ans))
	print(*ans)