#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void main() {
	//Get input
	printf("Enter number to count up to\n");
	long max = 2;
	scanf("%d",&max);
	max = max<2?2:max; //Lock input range
	//Setup of array
	char numbers[max];
	printf("I will count up to: %d", sizeof(numbers));
	memset(&numbers[0],0,sizeof(numbers));
	//Begin alg
	register char value = 0;
	for (int i=2;i<max;i++) {
		value = numbers[i];
		if(value==0) { //If prime
			printf("%d, ", i);
			for (int j=i;j<max;j+=i) { //sieve it
				numbers[j]=1;
			}
		}
	}
}