#include using namespace std; using ll = long long; using VI = vector; using VL = vector; using PII = std::pair; using PLL = std::pair; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--) #define rep2(i, s, n) for (int i = (s); i < (int)(n); i++) #define allpt(v) (v).begin(), (v).end() #define allpt_r(v) (v).rbegin(), (v).rend() const int mod = 1e9 + 7; const string wsp = " "; const string tb = "\t"; const string rt = "\n"; template void show1dvec(vector v) { int n = v.size() - 1; rep(i, n) cout << v[i] << wsp; cout << v[n] << rt; return; } template void show2dvec(vector> v) { int n = v.size(); rep(i, n) show1dvec(v[i]); } int main() { #ifdef DEBUG cout << "DEBUG MODE" << endl; ifstream in("input.txt"); //for debug cin.rdbuf(in.rdbuf()); //for debug #endif int n; double x, y; double b; cin >> x >> y >> n; vector a(n); bool ok = true; rep(i, n) cin >> a[i]; rep(i, n - 1) { if (a[i] * (y / x) > a[i + 1] ) ok = false; } cout << (ok ? "YES" : "NO") << rt; return 0; }