#lang racket

(define example '((balaur . 1) (dwarf . 13) (hobbit . 1) (wizard . 1) (foods . 5)))

(define (find x mset)
  (let ((res (filter (λ (p) (equal? (car p) x)) mset))) ; sau assoc
    (if (null? res) #f (cdar res))))

(define (cardinal mset) (apply + (map cdr mset)))

(define (add x mset)
  (if (find x mset)
      (map (λ (p) (if (equal? (car p) x) (cons (car p) (add1 (cdr p))) p)) mset)
      (cons (cons (x 1)) mset)))

(define (intersect ms1 ms2)
  (map (λ (k) (cons k (min (find k ms1) (find k ms2))))
       (filter (λ (k) (assoc k ms2)) (map car ms1))))