#include<iostream>
#include<stack>
using namespace std;
int main() {
	int n,ans=0,i,count=0;
	int dp[100][100];
	for (int i = 0; i < 100; i++) {
		for (int j = 0; j < 100; j++) {
			dp[i][j] = -1;
		}
	}
	while (cin >> n) {
		for (i = 2; i <= n; i++) {
			for (int j = 2; j <= i; j++) {
				if (dp[i][j] == -1) {
					dp[i][j] = i%j;
				}
				if (dp[i][j] == 0 ) {
					count++;
				}
			}
			if (count == 1) {
				ans++;
			}
			count = 0;
		}
		cout << ans << endl;
		ans = 0;
	}
	return 0;
}