#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    const double eps = 1e-10;
    double x, y;
    cin >> x >> y;
    x = x * 1000 / 3600;
    y = y * 1000 / 3600;
    ll n;
    cin >> n;
    vector<double> a(n);
    rep(i, n) cin >> a[i];
    rep(i, n - 1) {
        double t = a[i] / x;
        double s = t * y;
        // printf("s=%.10f, a[%lld]=%.10f, next=%.10f\n", s, i, a[i], a[i + 1]);
        if (s > (a[i + 1] + eps)) {
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;
    return 0;
}