#include <iostream>
#include <vector>

using namespace std;

int main() {
	int x, y, n, a;
	vector<int> v;
	double xx, yy;
	double d = 0;
	double dv = 0;
	double t;
	bool flag = false;

	cin >> x >> y >> n;

	xx = x * 1000.0 / 60.0 / 60.0;
	yy = y * 1000.0 / 60.0 / 60.0;

	dv = yy - xx;

	for (int i = 0; i < n; i++) {
		cin >> a;
		v.push_back(a);
	}

	for (int i = 0; i < n - 1; i++) {
		t = v[i] / xx;
		
		d += dv * t;

		if (d > v[i + 1]) {
			cout << "NO" << endl;
			flag = true;
			break;
		}
	}

	if (flag == false) {
		cout << "YES" << endl;
	}
}