Parallel computation of primes

primes.c

#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <sys/types.h>  
#define number_of_procs 4
int main() {
    long i, j, prime, low, high,count_left=0,count_right=0;
    pid_t p;
    low = 3;
    high = 11;
    long chunck = ceil((high-low)/number_of_procs);
    long start = low;
    for (int k=0; k<number_of_procs; k++){
        p = fork();
        if (p==0){
            int end=0;
            if (start+chunck > high){
                end = high;
            }
            else{
                end = start + chunck;
            }
            
            for (i=start; i<=end; i++){
                prime=1;
                if (i%2==0){
                    prime=0;
                }
                for (j=3; j<(sqrt(i)+1); j+=2){
                    if ( (i%j) ==0){
                        prime=0;
                        break;
                    }
                }
                if (prime){
                    printf("%ld is a prime\n",i);
                }
            }
            break;
        }
        else {
            start += chunck + 1;
        }
    }

}