import sys
input = sys.stdin.readline

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

S=set()
right=N-1
left=0
for i in range(N):
    S.add(A[i])
    if len(S)!=i+1:
        right=i
        break

S=set()
for i in range(N):
    S.add(A[N-1-i])
    if len(S)!=i+1:
        left=N-1-i
        break

ANS=[]
for i in range(left+1,right+1):
    ANS.append(i)

print(len(ANS))
print(*ANS)