(define (System.out.println x)
  (begin
    (display x)
    (newline)
  )
)

(let (
      (H (read))
      (W (read))
      (N (read))
      (K (read))
     )
  (if (or (= K (modulo (* H W) N)) (and (= K N) (= (modulo (* H W) N) 0)))
      (System.out.println "YES")
      (System.out.println "NO")
  )
)