def PR(a):

    if a!=2:

        f=0

        for i in range(2,a):

            if a%i==0:

                f=1

                break

        if f==0:

            return True

        else:

            return False

    else:

        return True 

h=0#sdfxvfcv         

n=int(input())                        

for i in range(1,n+1):

    a=[]

    k=0

    for j in range(2,i+1):

        if PR(j):

            a.append(j)

    for j in a:

        if i%j==0:

            k+=1

    if k==2:

        h+=1

print(h)