#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int, int> P;


int main()
{
	double x, y;
	cin >> x >> y;
	x = x * 1000 / 60 / 60;
	y = y * 1000 / 60 / 60;
	int n;
	cin >> n;
	ll a[n];
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	for (int i = 0; i < n-1; i++) {
		double t = a[i]/x;
		double shisyo = t * y;
		if (shisyo>a[i+1]) {
			cout << "NO" << "\n";
			return 0;
		}
	}
	cout << "YES" << "\n";
	return 0;
}