#include <bits/stdc++.h>
using namespace std;
#define LONG_INF 10000000000000000
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
int main() {
	double x, y;
	cin >> x >> y;
	x /= 3.6;
	y /= 3.6;
	vector<double> hoge;
	int h = 0;
	cin >> h;
	REP(i, h) {
		double a;
		cin >> a;
		hoge.push_back(a);
	}
	for (int i = 0;i < h - 1;++i) {
		double time = hoge[i] / x;
		if (hoge[i + 1] / y > time) {
			cout << "YES" << endl;
			return 0;
		}
	}
	cout << "NO" << endl;
	return 0;
}