#include<iostream>
#include<string>

using namespace std;

#define NMAX 100000
int main(){

	double X,Y;
	double Xa;
	int N;
	double a;

	cin>>X>>Y;
	cin>>N;
	cin>>a;
	for(int i=0;i<N-1;i++){
		Xa=a/X;
		cin>>a;
		if(Xa*Y>a){
			cout<<"NO"<<endl;
			return 0;
		}
	}

	cout<<"YES"<<endl;
	return 0;
}