Add Two Numbers

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

#include<stdio.h>#include<stdlib.h>typedef struct ListNode {    int val;    struct ListNode *next;}ListNode;ListNode *addTowNumbers(ListNode *l1, ListNode *l2) {    ListNode *p1 = l1, *p2 = l2, *head;    int data = 0, carry = 0, i = 1, j = 1;    int data1 = 0, data2 = 0;    if(l1 == NULL && l2 == NULL) return NULL;    head = p1 = p2 =(ListNode *)malloc(sizeof(ListNode));    while(l1 != NULL || l2 != NULL || carry == 1) {        p2->next = p1;        p2 = p1;        if(l1 != NULL) {            data1 = l1->val;            l1 = l1->next;        }        else data1 = 0;        if(l2 != NULL) {            data2 = l2->val;            l2 = l2->next;        }        else data2 = 0;        data = data1 + data2 + carry;        if(data >9) carry = 1;        else carry = 0;        p1->val = data%10;        p1 =(ListNode *)malloc(sizeof(ListNode));    }    p2->next = NULL;    return head;}void main() {    int data,n=0;    ListNode *head,*head1,*p1,*head2,*p2,*p3;    p1=p2=(ListNode *)malloc(sizeof(ListNode));    scanf("%d",&data);    p1->val=data;    head1=NULL;    while(data!=0){        n++;        if(n==1) head1=p1;        else            p2->next=p1;        p2=p1;        p1=(ListNode *)malloc(sizeof(ListNode));        scanf("%d",&data);        p1->val=data;    }    p2->next=NULL;    p1=p2=(ListNode *)malloc(sizeof(ListNode));    scanf("%d",&data);    p1->val=data;    head2=NULL;    n=0;    while(data!=0){        n++;        if(n==1) head2=p1;        else p2->next=p1;        p2=p1;        p1=(ListNode *)malloc(sizeof(ListNode*));        scanf("%d",&data);        p1->val=data;    }    p2->next=NULL;    p1=head1;    p2=head2;    while(p1) {printf("%d,",p1->val);p1=p1->next;}    while(p2) {printf("%d,",p2->val);p2=p2->next;}    head = addTowNumbers(head1, head2);    p3 = head;    while(p3) {printf("%d,",p3->val);p3=p3->next;}    printf("\n");}