#include<iostream>
#include<stdio.h>
#include<math.h>
#include<vector>

#define INF 999999
using namespace std;

int main()
{
	int n;
	
	while (cin >> n)
	{
		int ans = 0,rootn;

		int a[INF] = {0};
		
		rootn = sqrt(n)+1;
	
		for (int i = 2; i <= rootn; i++)
		{
			if (a[i]==0)
			{
				for (int j = i+1; j <= INF; j++)
				{
					if (a[j] == 0 && j%i == 0)
					{
						a[j] = 1;
					}
				}
			}
		}
		cout << "a" << endl;
		for (int i = 2; i <= n; i++)
		{
			if (a[i]==0)
				++ans;
		}
		cout << ans << endl;
	}
			
	return 0;
}