from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right, insort
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

nums = list(map(int, input()))
N = len(nums)

M = 2*2
dp = [[-1]*M for _ in range(N+1)]
def ind(small, d): return small*2+d
dp[0][ind(0, 0)] = 0
for i in range(N):
    num = nums[i]
    for d in range(2):
        for small in range(2):
            key = ind(small, d)
            if dp[i][key] < 0: continue
            for nd in [4, 5]:
                if not small and nd > num: break
                nsmall = small | (1 if nd < num else 0)
                nkey = ind(nsmall, nd-4)
                dp[i+1][nkey] = key
ans = 0
for d in reversed(range(2)):
    for small in range(2):
        if dp[N][ind(small, d)] < 0: continue
        i = ind(small, d)
        cur = N
        li = []
        for _ in range(N):
            li.append(str(i%2+4))
            i = dp[cur][i]
            cur -= 1
        li.reverse()
        ans = max(ans, int("".join(li)))

ans = max(ans, int("5"*(N-1)))
print(ans)