#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; templatebool chmax(T &a, const T &b) { return (abool chmin(T &a, const T &b) { return (b vi; typedef vector vl; typedef pair pii; typedef pair pll; typedef int _loop_int; #define rep(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i) #define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i) #define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i) #define DEBUG(x) cout<<#x<<": "< vi; typedef pair pii; int main() { int X, Y; cin >> X >> Y; int N; cin >> N; vector A(N); for (int i = 0; i < N; i++) { cin >> A[i]; } for (int i = 0; i < N - 1; i++) { if (A[i] * Y > A[i - 1]*X) { cout << "NO" << endl; return 0; } } cout << "YES" << endl; return 0; }