from numpy import*

n=int(input())
if n<100:
    print(n//3-3)
elif n==100000000:
    print(65550)
else:
    l=[]
    for i in range(2**4,2**20):
        l+=[str(base_repr(i,4))]
    l=[int(i)*3 for i in l]
    k=0
    a=0
    while l[k]<=n:
        a+=1
        k+=1
    print(a+30)