prime

#include <stdio.h>
#include <math.h>
unsigned int n_from, n_to,n[]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101},prime,riza,kr;
int main(void)
{
//--------------------------------------------------------
//---------------------------------------------------------
FILE * in = fopen ("function.in", "r");
   FILE * out = fopen ("function.out", "w");
   fscanf (in , "%d %d", &n_from, &n_to);
 //--------------------------------------------------------
//---------------------------------------------------------
if (n_from > n_to)
{
  kr=n_from;
  n_from=n_to;
  n_to=kr;

}

n_from++;
//--------------------------------
if (n_from == 2)
   n_from++;
while (n_from < n_to)
{
    riza=sqrtf(n_from);

      if(prime==1)
      goto kalo_loop;

 //--------------------------------------------------------------------------------

    kr=0;
    for (n[kr]; n[kr] <= riza; kr++)   // check if prime
          {
           if ((n_from % n[kr]) == 0)
             {n_from--;
              goto loop;
              }

            }

    //--------print----------------------------------------
        fprintf(out,"%d", n_from);

         prime=1;
         goto loop;

//-------------------------------------------------------------------------------------------
//-----------------------------------------------------------------------------------------
 kalo_loop:

      kr=0;
    for (n[kr]; n[kr] <= riza; kr++)   // check if prime
          {
           if ((n_from % n[kr]) == 0)
             goto loop;

            }

//----------print---------------
//----------print----------------
        fprintf(out," %d", n_from);

 loop:
n_from+=2;
    }
 if (prime == 1)
 fprintf(out,"\n");
   end:
   fclose(in); fclose(out);
   return 0;
   }