import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.stream.Stream;

import static java.lang.System.in;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String[] inputs = reader.readLine().split(" ");
        int X = Integer.parseInt(inputs[0]);
        int Y = Integer.parseInt(inputs[1]);
        double X1 = X * 1000 / 3600.0;
        double Y1 = Y * 1000 / 3600.0;

        int N = Integer.parseInt(reader.readLine());
        inputs = reader.readLine().split(" ");
        boolean canChase = true;

        int[] intersections = Stream.of(inputs).mapToInt(Integer::parseInt).toArray();

        for (int i = 0; i < N; i++) {
            int intersection = Integer.parseInt(inputs[i]);
            double time = intersection / X1;

            double masterPosition = time * Y1;
            for (int j = i + 1; j < N; j++) {
                if (masterPosition > intersections[j]) {
                    canChase = false;
                    break;
                }
            }
            if (!canChase) {
                break;
            }
        }

        if (canChase) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }

}