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

signed main(){
	double x, y;
	cin >> x >> y;
	x = x / 3600. * 1000;
	y = y / 3600. * 1000;
		
	int n;
	cin >> n;
	vector<double> v(n);
	for(int i = 0; i < n; i++)cin >> v[i];
	
	double koba, shisho;
	bool ok = true;

	for(int i = 0; i < n - 1; i++){
		koba = v[i] / x;
		shisho = koba * y;
		if(shisho >= v[i + 1])ok = false;
		//cout << koba << endl;
	}
	cout << (ok ? "YES" : "NO") << endl;
}