OpenMP to POSIX Threads

I am trying to execute the code below using POSIX Threads instead of OpenMp. Any ideas. I am newbee. I have tried several times and it is not working.

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

  main(int argc, char *argv[])  {
      int i, j, limit;
      int start, end;          /* range of numbers to search */
      int number_of_primes = 0;  /* number of primes found */
      int number_of_41primes = 0;/* number of 4n+1 primes found */
      int number_of_43primes = 0;/* number of 4n-1 primes found */
      int prime;               /* is the number prime? */
      int print_primes = 0;      /* should each prime be printed? */

      start = atoi(argv[1]);
      end = atoi(argv[2]);
      if (!(start % 2))
          start++;

      if (argc == 4 && atoi(argv[3]) != 0)
           print_primes = 1;
       printf("Range to check for Primes: %d - %d ",start, end);

       #pragma omp parallel for private (limit, j, prime)
       for(i = start; i <= end; i += 2) {

            limit = (int) sqrt((float)i) + 1;
            prime = 1; /* assume number is prime */
            j = 3;
            while (prime && (j <= limit)) {
              if (i%j == 0) prime = 0;
              j += 2;
            }

            if (prime) {
            if (print_primes) printf("%5d is prime",i);
            #pragma critical
            {
                number_of_primes++;
                if (i%4 == 1) number_of_41primes++;
                if (i%4 == 3) number_of_43primes++;
            }
         } 
       }

  printf("\n Program Done.\n  %d primes found \n",number_of_primes);
  printf("\nNumber of 4n+1 primes found: %d \n",number_of_41primes);
  printf("\nNumber of 4n-1 primes found: %d \n",number_of_43primes);
}