package main

import (
	"fmt"
	"bufio"
	"os"
	)
	
func main() {
	rd := bufio.NewReader(os.Stdin)
	
	var n int
	var s,b,h int64
	
	fmt.Fscan(rd,&n,&s,&b,&h)
	
	for i,g,y:=1,h,h;i<n;i,g=i+1,h {
		t := g+s*b
		if t>y {
			y=t
		}
		fmt.Fscan(rd,&h)
		if h<=y {
			continue
		}
		fmt.Println("No")
		return
	}
	
	fmt.Println("Yes")
}