import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
INF = 2 ** 63 - 1
mod = 998244353
import bisect
n = ii()
a = li()
def LIS1(a):

    dp = [INF] * n

    ind = [-1] * n

    for i in range(n):
        now = bisect.bisect_left(dp, a[i])
        dp[now] = a[i]
        ind[i] = now

    k = max(ind) + 1
    ans = [0] * k
    k -= 1
    for i in range(n - 1, -1, -1):
        if ind[i] == k:
            ans[k] = i
            k -= 1
    return ans

def LDS(a):
    b = [-i for i in a[::-1]]
    dp = [INF] * n

    ind = [-1] * n

    for i in range(n):
        now = bisect.bisect_left(dp, b[i])
        dp[now] = b[i]
        ind[i] = now

    k = max(ind) + 1
    ans = [0] * k
    k -= 1
    for i in range(n - 1, -1, -1):
        if ind[i] == k:
            ans[k] = n - i - 1
            k -= 1

    return ans

ans1 = set(LIS1(a))
ans2 = set(LDS(a))
ans = ans1 & ans2

ans = list(sorted(ans))
print(len(ans))
print(*[a[i] for i in ans])