from collections import defaultdict

N=int(input())
A=list(map(int,input().split()))
idx=defaultdict(list)
for i in range(N):
    idx[A[i]].append(i)
l,r=0,N-1
for a,lst in idx.items():
    if len(lst)>=3:
        l,r=N,0
    elif len(lst)==2:
        i,j=lst
        l=max(l,i)
        r=min(r,j)
ans_lst=[i+1 for i in range(l,r)]
print(len(ans_lst))
print(*ans_lst)