#include<iostream>
#include<vector>
#include<math.h>

using namespace std;

int main() {

	int x, y, n;
	cin >> x >> y >> n;
	vector<int> kousaten;
	for (int i = 0;i < n;i++) {
		int buf = 0;
		cin >> buf;
		kousaten.push_back(buf);
	}
	double xs = x * pow(10, 3) / pow(60, 2);
	double ys = y * pow(10, 3) / pow(60, 2);

	double koba_now_s = kousaten[n-2] / xs;
	double master_p = ys * koba_now_s;
	if (master_p<kousaten[n-1])cout << "YES" << endl;
	else cout << "NO" << endl;

	return 0;
}