Pointer to Pointer

#include<stdio.h>
#include<conio.h>
void main()
{
int a=5;
int *p1,**p2,***p3;
clrscr();
p1=&a;
p2=&p1;
p3=&p2;
*p1=10;
printf("a=%d\n",a);
**p2=15;
printf("a=%d\n",a);
***p3=20;
printf("a=%d\n",a);
getch();
}


OUTPUT:

a=10

a=15

a=20