n = int(input())


sum = 0
for i in range(1,n+1):   # 如果是7的倍数记录下来
    if i % 7 == 0:
        sum += 1
        continue
    
    s = str(i)
    if s.count('7') > 0: # 如果含7
        sum += 1

print(sum)