from collections import defaultdict
def Eratosthenes(N):
  is_prime = [1 for i in range(N+1)]
  is_prime[0] = is_prime[1] = 0
  P = []
  for p in range(2,N+1):
    if is_prime[p] == 0:
      continue
    P.append(p)
    for d in range(2,N//p+1):
      q = p*d
      is_prime[q] = 0
  return P

N = int(input())
P = Eratosthenes(300000)
P = P[::-1]
cout = [0 for i in range(300001)]
Q = []
ans = 0
m = 0
while len(P):
  c = P.pop()
  if c > N:
    break
  for p in reversed(P):
    if p - c > m:
      break
    ans += cout[p-c]
  for p in Q:
    cout[p+c] += 1
  if c >= 3:
    m = Q[-1] + c
  Q.append(c)
print(ans)