题解 | #挑7#
挑7
https://www.nowcoder.com/practice/ba241b85371c409ea01ac0aa1a8d957b
num = int(input().strip())
re = num//7
list1 = [i*7 for i in range(1,re+1)]
list2 = []
for k in range(1,num+1):
if str(k).count('7') >= 1:
list2.append(k)
list3 = set(list1+list2)
print(len(list3))
