#include <cstdlib>
#include <cstdio>
#include <ctime>
int main ( int argc, char *argv[] );
int prime_part ( int id, int p, int n );

int main ( int argc, char *argv[] )
{
	int id;
	int n = 100000;
	int p;
	int total;
	int total_part;
	p = 4;
	    // Check for correct number of arguments
    if (argc == 2) {
		n = std::atoi(argv[1]);
    } else if (argc > 2) {
		printf("Usage: %s [n]\n", argv[0]);
		return 1;
	}

	total = 0;
	for ( id = 0; id < p; id++ )
	{
		total_part = prime_part ( id, p, n );
		total = total + total_part;
	}
	printf ( "\n" );
	printf ( "Between 2 and %d, there are %d primes\n", n, total );
	return 0;
}
int prime_part ( int id, int p, int n )
{
	int i;
	int j;
	int prime;
	int total_part;
	total_part = 0;
for ( i = 2 + id; i <= n; i = i + p )
	{
		prime = 1;
 
		for ( j = 2; j < i; j++ )
		{
			if ( i % j == 0 )
			{
				prime = 0;
				break;
			}
		}
		if ( prime )
		{
			total_part = total_part + 1;
		}
	}
	return total_part;
}