a=int(input())
flag=1
book=1
cnt=0;
for i in range(1,a):
    flag=1
    book=1
    for j in range(1,len(chr(i))):
        k=chr(i)
        if j%2!=0:
            if int(k[j])%2!=0:
                flag=2
        if j%2==0:
            if int(k[j])%2==0:
                book=2;
    if book==2 and flag==2:
        cnt+=1
print(cnt)