/*No.512 魔法少女の追いかけっこ*/
import java.util.*;
public class No512 {
	public static void main(String[] args) {
		try(Scanner input =new Scanner(System.in)){
			float speed[]=new float[2];
			float rapTime,rapPoint;
			boolean chase=true;
			for(int i=0;i<speed.length;i++){
				speed[i]=input.nextByte()*1000f/3600f;
			}
			byte Intersection=input.nextByte();
			int interval[]=new int[Intersection];
			for(int i=0;i<Intersection;i++){
				interval[i]=input.nextInt();
			}
			for(int i=0;i<interval.length-1;i++){
				rapTime=interval[i]/speed[0];
				rapPoint=speed[1]*rapTime;
				if(rapPoint>interval[i+1]){
					chase=false;
					break;
				}
			}
			if(chase){
				System.out.println("YES");
			}else{
				System.out.println("NO");
			}
		}catch(Exception e){
			e.printStackTrace();
		}
	}
}