#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int A[100];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int X, Y;
	int N;
	cin >> X >> Y >> N;
	for(int i = 0; i < N; i++) {
		cin >> A[i];
	}

	for(int i = 0; i < N - 1; i++) {
		double t = (double)A[i] / X;
		double l = Y * t;
		if(A[i + 1] < l + 1e-10 && Y * A[i] != A[i + 1] * X) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
}