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

lo = 0
hi = N - 1

s = set()
for i, a in enumerate(A):
    if a in s:
        hi = i
        break
    s.add(a)

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

ret = []
while lo < hi:
    ret.append(lo)
    lo += 1

print(len(ret))
print(" ".join(str(x + 1) for x in ret))