poly mult

#include<stdio.h>
#include<stdlib.h>

struct node{
    int coeff,expo;
    struct node*link;
}
*phead,*qhead,*rhead;

struct node* Readpoly(){
    struct node*new,*ptr,*head=NULL;
    int n,i;
    printf("enter number of terms");
    scanf("%d",&n);
    printf("enter coeff and expo");
    for(i=1;i<=n;i++){
        printf("enter (coef%d,expo%d)",i,i);
        new=(struct node*)malloc(sizeof(struct node));
        scanf("%d",&new->coeff);
        scanf("%d",&new->expo);
        new->link=NULL;
        if(head==NULL){
            head=new;
            ptr=head;
        }
        else{
            ptr->link=new;
            ptr=new;
        }
    }
    return(head);
}
void Displaypoly(struct node*head){
    struct node*ptr;
    if(head==NULL){
        printf("poly is emptu");
    }
    else{
        ptr=head;
        while(ptr->link!=NULL){
            printf("%dx^%d + ",ptr->coeff,ptr->expo);
            ptr=ptr->link;
        }
        printf("%dx^%d\t ",ptr->coeff,ptr->expo);
    }
        }
  struct node* mulpoly(){
      struct node*new,*p,*q,*r,*head=NULL,*prev;
      p=phead;
      q=qhead;
     
      
      while(p!=NULL){
          while(q!=NULL){
              new=(struct node*)malloc(sizeof(struct node));
              new->coeff=p->coeff*q->coeff;
              new->expo=p->expo+q->expo;
              new->link=NULL;
          if(head==NULL){
               head=new;
               r=head;
           }
           else{
               r->link=new;
               r=new;
           }
           q=q->link;
          }
          p=p->link;
          q=qhead;
      }
      p=head;
      while(p!=NULL){
          prev=p;
          q=p->link;
          while(q!=NULL){
              if(p->expo==q->expo){
              (p->coeff=p->coeff+q->coeff);
              prev->link=q->link;
              free(q);
              q=prev->link;
          }
          else{
              prev=q;
              q=q->link;
          }
          }
          p=p->link;
      }
      return(head);
  }
  
      

         
      void main(){
    printf("enter details of firsr poly");
    phead=Readpoly();
        printf("enter details of second poly");
    qhead=Readpoly();
    printf("first polynomail");
    Displaypoly(phead);
     printf("second polynomail");
    Displaypoly(qhead);
    rhead=mulpoly();
    printf("resultant poly");
    Displaypoly(rhead);
}