import sys
input = sys.stdin.readline

x=int(input())

#x=5*10**5

import math 
L=math.floor(math.sqrt(x))#平方根を求める

Primelist=[i for i in range(x+1)]
Primelist[1]=0#1は素数でないので0にする.
 
for i in Primelist:
    if i>L:
        break
    if i==0:
        continue
    for j in range(2*i,x+1,i):
        Primelist[j]=0

Primes=[Primelist[j] for j in range(x+1) if Primelist[j]!=0]
SP=set(Primes)

ANS=0
for b in Primes:
    if b>math.sqrt(x):
        break

    for y in Primes:
        if y>b**2:
            break
        if b**2-y in SP:
            ANS+=1

print(ANS)