01 #include<stdio.h>
02 
03 int main()
04 {
05     int i,j=2,ch=0;
06 
07     printf("nENTER ANY NUMBER ");
08     scanf("%d",&i);
09     while(j<=i/2)
10     {
11         if(i%j==0)
12         {
13             printf("%d IS NOT PRIME",i);
14             ch=1;
15             break;
16         }
17         else
18         {
19             j++;
20         }
21     }
22     if(ch==0)
23     {
24         printf("%d IS PRIME",i);
25     }
26 }

OUTPUT :
 
 (1st Run)
 
 ENTER ANY NUMBER 5
 5 IS PRIME
 
 (2nd Run)
 
 ENTER ANY NUMBER 6
 6 IS NOT PRIME