struct phonebook {
	char username[64],region[64];
	int code,time,used;
	struct phonebook *nxt;
};


struct phonebook *root;

struct phonebook *find (const char username[]) {
	struct phonebook *l;
	for (l=root; strcmp(l->username,username)!=0 && l!=NULL; l=l->nxt) {
	}
	return(l);
}