package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
)

func main() {
	sc := NewScanner(os.Stdin)
	H, _ := sc.NextInt()
	W, _ := sc.NextInt()
	N, _ := sc.NextInt()
	K, _ := sc.NextInt()

	fmt.Println(solve(H, W, N, K))
}

func solve(h, w, n, k int) string {
	loser := h * w % n
	if loser == 0 {
		loser = n
	}
	if loser == k {
		return "YES"
	} else {
		return "NO"
	}
}

type Scanner struct {
	*bufio.Scanner
}

func NewScanner(r io.Reader) *Scanner {
	return &Scanner{
		bufio.NewScanner(r),
	}
}

func (s *Scanner) Next() (string, error) {
	s.Scanner.Split(bufio.ScanWords)
	return s.nextToken()
}

func (s *Scanner) nextToken() (string, error) {
	sc := s.Scanner
	if sc.Scan() {
		return sc.Text(), nil
	}
	if sc.Err() != nil {
		return "", sc.Err()
	}
	return "", io.EOF
}

func (s *Scanner) NextInt() (int, error) {
	token, err := s.Next()
	if err != nil {
		return 0, err
	}
	return strconv.Atoi(token)
}