import sys
input = sys.stdin.readline

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

# LIS(最長増加部分列)
import bisect


DP=[float("inf")]*N # DP[i]で、長さiのLISの最終要素の最小値.
POS=[-1]*N

for i in range(N):
    a=A[i]
    pos=bisect.bisect_left(DP,a)
    DP[pos]=a
    POS[i]=pos
    

ANS=0
for i in range(N):
    if DP[i]!=float("inf"): # float("inf")でない最小のものがLISの長さ
        ANS=i

LIST=[]
x=ANS
for i in range(N-1,-1,-1):
    if POS[i]==x:
        LIST.append(A[i])
        x-=1

#print(LIST)

A=[-a for a in A][::-1]

DP=[float("inf")]*N # DP[i]で、長さiのLISの最終要素の最小値.
POS=[-1]*N

for i in range(N):
    a=A[i]
    pos=bisect.bisect_left(DP,a)
    DP[pos]=a
    POS[i]=pos
    

ANS=0
for i in range(N):
    if DP[i]!=float("inf"): # float("inf")でない最小のものがLISの長さ
        ANS=i

LIST2=[]
x=ANS
for i in range(N-1,-1,-1):
    if POS[i]==x:
        LIST2.append(A[i])
        x-=1

SET=set(LIST)
SET2=set([-x for x in LIST2])

ANS=[]

A=[-a for a in A][::-1]

for a in A:
    if a in SET and a in SET2:
        ANS.append(a)
print(len(ANS))
print(*ANS)