/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
struct ListNode* deleteDuplicates(struct ListNode* head ) {
    // write code here
    struct ListNode *c = head;
    while(c != NULL) {
        while(c->next != NULL && c->val == c->next->val) {
            c->next = c->next->next;
        }
        c = c->next;
    }
    return head;
}