#エラトステネスの篩
def Sieve_of_Eratosthenes(N,mode=False):
    """Nまでのエラトステネスの篩を実行

    N:自然数
    mode:False->素数のリスト,True->素数かどうかのリスト
    (False->[2,3,5,...],True->[0,0,1,1,0,1,...])
    """

    if N==0:
        return [0]

    T=[1]*(N+1)
    T[0]=T[1]=0

    for x in range(4,N+1,2): T[x]=0
    for x in range(9,N+1,3): T[x]=0

    a=5
    Flag=0
    while a*a<=N:
        if T[a]:
            b=a*a
            c=2*a
            while b<=N:
                T[b]=0
                b+=c
        a+=2+2*Flag
        Flag^=1

    if mode:
        return T
    else:
        return [k for k in range(N+1) if T[k]]
#==================================================
N=int(input())
M=0
while (M+1)*(M+1)<=N:
    M+=1

Y=[0]*(N+1); Y[1]=1
A=list(range(N+1))

for p in Sieve_of_Eratosthenes(M):
    if p*p>N: break

    q=s=p*p
    Y[q]=1
    while q<=N:
        r=q
        while r<=N:
            A[r]//=s
            r+=q
        q*=p*p

for i in range(1,N+1): Y[i]+=Y[i-1]

K=0
for i in range(1,N+1):
    K+=Y[N//A[i]]

print(K)