def ip():return int(input())
def mp():return map(int, input().split())
def lmp():return list(map(int, input().split()))
# No.3240 Count 8 Included Numbers (Easy)
N = ip()
ans = 0
for i in range(1, N+1):
  s = str(i)
  if '8' in s:
    ans += 1
print(ans)