#include<bits/stdc++.h>
using namespace std;

double A[1001];

int main(){
	int n;
	double a,b;
	cin >> a >> b >> n;
	a=a*1000/3600;
	b=b*1000/3600;
	
	for(int i=0;i<n;i++){
		cin >> A[i];
	}
	
	for(int i=1;i<n;i++){
		if(A[i]*a<b*A[i-1]){
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
	return 0;
}