Polynomial addition through linked list

include<stdio.h>
#include<malloc.h>

struct poly

{

        int co;
        int exp;
        struct poly *ptr;
};

struct poly * Addelement(struct poly *,int,int);
struct poly * add(struct poly *,struct poly *);
void display(struct poly *);

int main()

{

        int num1,co,exp,num2,i;
        struct poly *p1,*p2,*p3;
        p1=NULL;
         p2=NULL;
        p3=NULL;

        printf(" \n The number of elements to be added to the 1st list ");
        scanf("%d",&num1);

        for(i=1;i<=num1;i++)
        {
                printf("\n Enter the Elements of 1st polynomial and coeff \n ");
                scanf("%d %d",&co,&exp);
                p1=Addelement(p1,co,exp);
        }

        printf(" \n The number of elements to be added to the 2nd list ");
        scanf("%d",&num2);

        for(i=1;i<=num2;i++)
        {
                printf("\n Enter the Elements of 2nd polynomial and coeff \n ");
                scanf("%d %d",&co,&exp);
                p2=Addelement(p2,co,exp);
        }
        printf("\n The elements of first polynomial are ");
        display(p1);
        printf("\n The elements of second polynomial are ");
        display(p2);
        p3=add(p1,p2);
        printf("\n The Added polynomial is \n");
        display(p3);
}

        struct poly * Addelement(struct poly *head,int co,int exp)
        {
                struct poly  *newnode;
                newnode=(struct poly *)malloc(sizeof(struct poly));
                newnode->co=co;
                newnode->exp=exp;
		 if(head==NULL)
                {
                        newnode->ptr=NULL;
                        return newnode;
                }

                else
                {
                        newnode->ptr=head;
                        return newnode;
                }
        }

        void display(struct poly *p3)

        {
                    if(p3==NULL)
                {

                        printf("\n The list is empty \n");
                }

                while(p3!=NULL)
                {
                        printf(" %dx^%d+ ",p3->co,p3->exp);
                        p3=p3->ptr;
                }
        }

struct poly * add(struct poly *p1,struct poly *p2)
{

        struct poly *p3,*temp;
        p3=NULL;
        if(p1==NULL&&p2==NULL)
        {
                printf("\n The list is empty \n");
        }


        while(p1!=NULL&&p2!=NULL)
        {
                temp=(struct poly *)malloc(sizeof(struct poly));
                if(p3==NULL)
                {

                        temp->ptr=NULL;
                        p3=temp;
                }

                else
                                 {
                        temp->ptr=p3;
                        p3=temp;
                }

                if(p1->exp>p2->exp)
                {
                        temp->co=p1->co;
                        temp->exp=p1->exp;
                        p1=p1->ptr;
                }

                else if(p2->exp>p1->exp)
                {
                        temp->co=p2->co;
                        temp->exp=p2->exp;
                        p2=p2->ptr;
                }
		else if(p1->exp==p2->exp)
                {
                        temp->co=p1->co+p2->co;
                        temp->exp=p1->exp;
                        p1=p1->ptr;
                        p2=p2->ptr;
                }
	}
while(p1!=NULL)

        {
                temp=(struct poly *)malloc(sizeof(struct poly));
                temp->co=p1->co;
                temp->exp=p1->exp;
                temp->ptr=p3;
                p3=temp;
                p1=p1->ptr;
        }

         while(p2!=NULL)

        {
                temp=(struct poly *)malloc(sizeof(struct poly));
                temp->co=p2->co;
		 temp->exp=p2->exp;
                temp->ptr=p3;
                p3=temp;
                p2=p2->ptr;
        }

return p3;
}