#include<fstream>
#include<iostream>
#include<vector>
#include<bitset>
using namespace std;

int main()
{
	long long n,num=1;
	fstream fin("ciur.in", fstream::in);
	fstream fout("ciur.out", fstream::out);
	fin>>n;
	bitset<2000002> bits;

	for(int i=1; (i<<1)+1<n; ++i)
	{
		if( ((i<<1)+1)*((i<<1)+1)>n)
			break;
		if(!bits[i])
		{
			for(long long j=i; ((i<<1)+1)*((j<<1)+1)<n; ++j)
			{
				const long long index=((i<<1)+1)*((j<<1)+1);
				//cout<<"("<<((i<<1)+1)*((j<<1)+1)<<" "<<(i+j)+1<<")"<<" ";
				bits[index>>1]=1;
			}
		}
	}
	for(int i=1; (i<<1)+1<n; ++i)
	{
		if(!bits[i])
		{
			num++;
			//cout<<(i<<1)+1<<" ";
		}
	}
	
	fout<<num<<endl;
	//cout<<endl<<num<<endl;

	fin.close();
	fout.close();
	return 0;
}