void przeob(node **head){
     if(*head){
        struct tnode *ele=*head;
        node *prev = NULL;
        while(ele->next){
            if(ele -> value < 0){
                if(!prev){
                    node *temp=(*head)->next;
                    free(head);
                    *head=temp;
                }
                else
                    prev -> next = ele -> next;
                node *temp=ele->next;
                free(ele);
                ele=temp;
            } else{
                prev = ele;
                ele = ele -> next;
            }
        }
        ele -> next = *head;
        if(ele->value < 0){
            if(!prev){
                *head = NULL;
            }else{
                prev -> next = *head;
                free(ele);
            }
        }
     }
}