import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {

	public static void main(String[] args) {
		new Main().run();
	}
	
	void run() {
		Scanner sc = new Scanner(System.in);
		int N=sc.nextInt();
		boolean[] isPrime=new boolean[N+1];
		Arrays.fill(isPrime, true);
		isPrime[0]=isPrime[1]=false;
		int sz=0;
		for(int i=2;i<isPrime.length;++i) {
			if(!isPrime[i])continue;
			++sz;
			for(int j=2*i;j<isPrime.length;j+=i) {
				isPrime[j]=false;
			}
		}
		int[] primes=new int[sz];
		sz=0;
		int ans=0;
		for(int i=0;i<isPrime.length;++i)if(isPrime[i])primes[sz++]=i;
		for(int i=0;i<primes.length&&primes[i]*primes[i]<=N;++i) {
			for(int j=0;j<primes.length;++j) {
				int res=primes[i]*primes[i]-primes[j];
				if(res<0)break;
				if(Arrays.binarySearch(primes, res)>=0)++ans;
			}
		}
		System.out.println(ans);
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}