// yukicoder: No.843 Triple Primes
// 2019.6.29 bal4u

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

#define MAX  1000000
#define SQRT 1000
char nop[MAX+5] = { 1,1,0,0,1 };			// zero: if prime 

void sieve() {
	int i, j;
	for (i = 3; i <= SQRT; i += 2) if (!nop[i]) {
		for (j = i * i; j <= MAX; j += i) nop[j] = 1;
	}
}

int main()
{
	int i, b, N, ans;

	sieve();
	scanf("%d", &N);
	
	if (N < 4) ans = 0;
	else {
		ans = 0, b = (int)sqrt((double)(N << 1));
		for (i = 3; i <= b; i+=2) if (!nop[i] && !nop[i*i-2] && i*i-2 <= N) ans++;
		ans <<= 1, ans++;
	}
	printf("%d\n", ans);
	return 0;
}