from operator import itemgetter
from itertools import *
from bisect import *
from collections import *
from heapq import *
import sys

sys.setrecursionlimit(10 ** 6)

def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def SI(): return sys.stdin.readline()[:-1]
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
int1 = lambda x: int(x) - 1
def MI1(): return map(int1, sys.stdin.readline().split())
def LI1(): return list(map(int1, sys.stdin.readline().split()))
p2D = lambda x: print(*x, sep="\n")
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

s=SI()
n=len(s)
ans=min(99,int(s))//3-3
if n>2:
    dp=[0]*(n+1)
    b=1
    for i,c in enumerate(s):
        if i==n-2:dp[i]-=1
        a=int(c)
        dp[i+1]+=dp[i]*4
        if b:dp[i+1]+=(a-1)//3+1
        if a%3:b=0
        #print(dp)
    ans+=dp[-1]+b
print(ans)