#include<iostream>
#include<string>
#include<vector>
#include<math.h>
using namespace std;

int count(string S) {
	return (S[0] == 'R'&&S[1] == 'E'&&S[2] == 'D') ? 1 : 0;
}

int main() {
	
	int x, y,z;
	int n;
	double dis;

	cin >> x >> y;
	cin >> n;
	vector<int> a(n);

	for (int i = 0; i < n; i++) cin >> a[i];
	x = x*(pow(10, 3)) / (60 * 60)+0.5;
	y = y*(pow(10, 3)) / (60 * 60)+0.5;
	for (int i = 0; i < n-1; i++) {
		dis = (double)a[i] / (double)x;
		z = y*dis;
		if (z>a[i+1]) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;

	return 0;
}