Polynomial Addtion in C

#include<stdio.h>
#include<conio.h>
#include<malloc.h>
struct link
{
int coeff;
int pow;
struct link *next;
};
struct link *poly1=NULL,*poly2=NULL,*poly=NULL;
void create(struct link *node)
{
char ch;
do
{
printf("\n Enter Co.eff");
scanf("%d",&node->coeff);
printf("\nEnter power:");
scanf("%d",&node->pow);
node->next=(struct link*)malloc(sizeof(struct link));
node=node->next;
node->next=NULL;
printf("\nContinue(y/n)");
ch=getch();
}
while(ch=='y'||ch=='Y');
}
void show(struct link *node)
{
while(node->next!=NULL)
{
printf("%dx^%d",node->coeff,node->pow);
node=node->next;
if(node->next!=NULL)
printf("+");
}
}
void polyadd(struct link *poly1,struct link *poly2,struct link *poly)
{
while(poly1->next && poly2->next)
{
if(poly1->pow>poly2->pow)
{
poly->pow=poly1->pow;
poly->coeff=poly1->coeff;
poly1=poly1->next;
}
else if(poly1->pow<poly2->pow)
{
poly->pow=poly2->pow;
poly->coeff=poly2->coeff;
poly2=poly2->next;
}
else
{
poly->pow=poly1->pow;
poly->coeff=poly1->coeff+poly2->coeff;
poly1=poly2->next;
poly2=poly2->next;
}
poly->next=(struct link *)malloc(sizeof(struct link));
poly=poly->next;
poly->next=NULL;
}
while(poly1->next||poly2->next)
{
if(poly1->next)
{poly->pow=poly1->pow;
poly->coeff=poly1->coeff;
poly1=poly1->next;
}
if(poly2->next)
{
poly->pow=poly2->pow;
poly->coeff=poly2->coeff;
poly2=poly2->next;
}
 poly->next=(struct link *)malloc(sizeof(struct link));
 poly=poly->next;
 poly->next=NULL;
 }}
void main()
 {
 char ch;
 clrscr();
 do
 {
 poly1=(struct link *)malloc(sizeof(struct link));
 poly2=(struct link *)malloc(sizeof(struct link));
 poly=(struct link *)malloc(sizeof(struct link));
 printf("Enter 1st number:");
 create(poly1);
 printf("Enter 2nd number:");
 create(poly2);
 printf("\n 1st number:");
 show(poly1);
 printf("\n 2nd number:");
 show(poly2);
 polyadd(poly1,poly2,poly);
 printf("\n Added polynomial:");
 show(poly);
 printf("\n Add 2 more numbers:");
//printf("\nContinue(y/n)");
 ch=getch();
 }
 while(ch=='y'||ch=='Y');
 }