Prime sieve (C)

//I'm so bored, send rescue

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

int main(int argc, char *argv [])
{
    if (argc != 2)
    {
        printf("I only want one argument, please!\n");
        return 1;
    }

    int N = atoi(argv[1]);
    int Primes[N+1];
    int i,j;

    for (i = 0; i <= N; i++)
        Primes[i] = 1;

    for (i = 2; i < N / i, Primes[i] == 1; i++)
    {
        for (j = 2; i * j <= N; j++)
            Primes[i * j] = 0;
    }

    for (i = 2; i <=N; i++)
        if (Primes[i] == 1) printf("%d,", i);

    printf("\n");
    return 0;
}