import java.io.*;

class Prime {
	boolean[] is_prime;
	int[] primes;
	
	void setPrime(int n) {
		int i, j;
		
		is_prime = new boolean[n + 1];
		is_prime[0] = false;
		is_prime[1] = false;
		for (i = 2; i <= n; i++) { is_prime[i] = true; }
		
		int cnt = 0;
		for (i = 2; i <= n; i++) {
			if (is_prime[i]) {
				for (j = i * 2; j <= n; j += i) {
					is_prime[j] = false;
				}
				cnt++;
			}
		}
		
		primes = new int[cnt];
		int id = 0;
		for (i = 2; i <= n; i++) {
			if (!is_prime[i]) continue;
			primes[id] = i;
			id++;
		}
	}
	
	int[] getPrimes() { return primes; }
	boolean isPrime(int x) { return is_prime[x]; }
};

class Solver {
	int[] cnts;
	
	public static void main(String[] args) {
		Solver solver = new Solver();
		solver.solve();
	}
	
	void solve() {
		int n = readInt();
		Prime prime = new Prime();
		prime.setPrime(3 * n);
		int[] primes = prime.getPrimes();
		initCnts(3 * n);
		
		cnts[primes[0] + primes[1]]++;
		
		long ans = 0;
		int max_exist = primes[0] + primes[1];
		for (int i = 2; i < primes.length && primes[i] <= n; i++) {
			for (int j = i + 1; j < primes.length && primes[j] - primes[i] <= max_exist; j++) {
				ans += cnts[primes[j] - primes[i]];
			}
			for (int j = 0; j < i; j++) {
				cnts[primes[i] + primes[j]]++;
			}
			max_exist = primes[i] + primes[i - 1];
		}
		
		System.out.println(ans);
	}
	
	int readInt() {
		try {
			BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
			String s = r.readLine();
			return Integer.parseInt(s);
		}
		catch (IOException e) {
			return 0;
		}
	}
	
	void initCnts(int n) {
		cnts = new int[n + 1];
		for (int i = 0; i <= n; i++) cnts[i] = 0;
	}
}