import bisect
N=int(input())
d=[""]
s=[]
for i in range(10):
    d=[i+j for i in d for j in "0369"]
    s+=d
a=set([])
for _ in s:
    a.add(int(_))
for i in range(12,99,3):
    a.add(i)
b=list(a)
b.sort()
p=0
while N>=int(b[p]):
    p+=1
ans=p-4
print(ans)