#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);++i)
#define all(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	double x, y;
	cin >> x >> y;
	int n;
	cin >> n;
	vector<double> A(n);
	rep(i, n) cin >> A[i];
	x = x / double(3600) * double(1000);
	y = y / double(3600) * double(1000);
	for (int i = 1; i < n;++i) {
		if (A[i] * x  < A[i - 1] * y) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
	return 0;
}