package main

import (
	"fmt"
	"log"
)

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

var eps float64 = 1e-9