package main

import "fmt"

func main() {
	var X, Y float64
	fmt.Scan(&X, &Y)
	x := X / 60 / 60 * 1000
	y := Y / 60 / 60 * 1000
	var N int
	fmt.Scan(&N)
	A := make([]float64, N)
	var a float64
	ans := "YES"
	for i := 0; i < N; i++ {
		fmt.Scan(&a)
		A[i] = a
	}
	for i := 1; i < N; i++ {
		d := A[i] - A[i-1]
		t := A[i] / y
		dy := A[i]
		dx := t * x
		// log.Println(d, t, dy, dx)
		if dy-dx > d {
			// log.Println("NO", dy-dx, d)
			ans = "NO"
			break
		}
	}
	fmt.Println(ans)
}