from collections import defaultdict
N=int(input())
A=list(map(int,input().split()))
C=[0 for _ in range(N)]
D=defaultdict(int)
for i,a in enumerate(A):
    D[a]+=1
    C[i]=D[a]
ans1=[]
for i,c in enumerate(C[:-1],1):
    if c==1:ans1.append(i)
    else:break
C=[0 for _ in range(N)]
D=defaultdict(int)
for i in range(N-1,-1,-1):
    D[A[i]]+=1
    C[i]=D[A[i]]
ans2=[]
for i in range(N-1,-1,-1):
    if C[i]==1:ans2.append(i)
    else:break
ans=sorted(set(ans1)&set(ans2))
print(len(ans))
print(*ans)