Compare two strings represented as linked lists

Given two linked lists, represented as linked lists (every character is a node in linked list). Write a function compare() that works similar to strcmp(), i.e., it returns 0 if both strings are same, 1 if first linked list is lexicographically greater, and -1 if second string is lexicographically greater.

Examples:
Input: list1 = g->e->e->k->s->a
       list2 = g->e->e->k->s->b
Output: -1

Input: list1 = g->e->e->k->s->a
       list2 = g->e->e->k->s
Output: 1

Input: list1 = g->e->e->k->s
       list2 = g->e->e->k->s
Output: 0
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