#define _USE_MATH_DEFINES #include <algorithm> #include <cstdio> #include <functional> #include <iostream> #include <cfloat> #include <climits> #include <cstdlib> #include <cstring> #include <cmath> #include <map> #include <queue> #include <set> #include <sstream> #include <stack> #include <string> #include <time.h> #include <vector> #include <random> using namespace std; #define rep(i, N) for (int i = 0; i < N; i++) #define pb push_back typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> i_i; typedef pair<ll, int> ll_i; typedef pair<double, int> d_i; typedef pair<ll, ll> ll_ll; typedef pair<double, double> d_d; struct edge { int u, v; ll w; }; int const MOD = 1000000007; ll _MOD = 1000000009; double EPS = 1e-12; int INF = INT_MAX / 2; int main() { int X, Y; cin >> X >> Y; int N; cin >> N; vector<int> a(N); rep(i, N) cin >> a[i]; rep(i, N - 1) { double t = (double)a[i] / X; if (t * Y > a[i + 1] + EPS) { cout << "NO" << endl; return 0; } } cout << "YES" << endl; }