#include <fstream.h>

int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");

	int ok[3000], i, j, n, s, ap = 0;

	fin >> n;
	memset (ok,1,sizeof(ok) );
	for ( i = 1; i*i <= n; i++ )
		for ( s = 1; s <= n; s++ )
			if ( ok[i/s] )
			{
				j = 2;
				while ( (i/s)*j <= n )
				{
					ok[(i/s)*j] = 0;
					j++;
				}
			}
		for ( i = 1; i <= n; i++ )
			for ( s = 1; s <= n; s++ )
				if ( ok[i/s] )
					ap++;

		fout << ap;



	return 0;
}