# EulerPolynomial-q9
# Section 17, Q.9, p.67, p.260
# input: 2398 or 4000

import sys
from prime import *

# sys.setrecursionlimit(10000) 
n = int(input("n=? "))
count = 0
for i in range(n+1):
  x = i
  f = x*x + x + 41
  if isPrime(f):
    count += 1
print("count ==" ,count)