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

d = {}
for i, a in enumerate(A):
    if not a in d:
        d[a] = []
    d[a].append(i)

if any(len(v) > 2 for v in d.values()):
    print(0)
    print()
    exit()

l, r = 0, N-1
for v in d.values():
    if len(v) == 2:
        l = max(l, v[0])
        r = min(r, v[1])

ans = [i+1 for i in range(l, r)]
print(len(ans))
print(*ans)