题解 | #挑7#

n = int(input())
ccount = 0

for i in range(1,n+1):
    if i % 7 == 0:      #1 i是7的倍数
        ccount += 1
    elif str(i).count('7') > 0:     #2 i中包含7
        ccount += 1

print(ccount)