Write a C program to find PRIME NUMBER and FACTOR

#include <stdio.h>
#include <conio.h>
void main()
{
 int flag,i,n,r,a[100],b,s;
 clrscr();
 printf("\n Enter Number: ");
 scanf("%d",&n);
 printf(" Facrtors are: 1 %d ",n);
 for(i=2;i<=n/2;i++)
 {
  r=n%i;
  if(r==0)
  {
   flag=s;
   a[b]=i;
   b++;
   printf("%d ",i);
  }
 }
 if(flag==s)
 {
  printf("\n So The Number %d is not prime",n);
 }
 else
 {
  printf("\n So The Number %d is prime",n);
 }
 getch();
}