N=int(input())

n=[1 for i in range(N+1)]
n[0]=0
n[1]=0

for i in range(2,N):
    if n[i]==1:
        for j in range(2,N):
            if i*j>N:
                break
            else:
                n[i*j]=0
#print(n)
S=dict()
for i in range(3,N+1):
    if n[i]==1:
        S[i]=i
#print(S)

ans=1
for i in S.keys():
    if S[i]**2-2 in S:
        ans+=2
if N==1:
    print(0)
else:
    print(ans)