import math,sys

N=int(input())
if N==1:
  print(0)
  sys.exit()

def searchPrimeNum(N):  # 素数列挙　こっち使う
  max = int(math.sqrt(N))
  searchList = [i for i in range(2,N+1)]
  primeNum = []
  while searchList[0] <= max:
    primeNum.append(searchList[0])
    tmp = searchList[0]
    searchList = [i for i in searchList if i % tmp != 0]
  primeNum.extend(searchList)
  return primeNum


table=searchPrimeNum(N)
cnt=0
for r in table:
  p=r**2-2
  if p in table:
    if p!=2:
      cnt+=2
    else:
      cnt+=1
print(cnt)