import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Tarek
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    }

    static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    }

    static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) BBattle solver = new BBattle(); solver new BBattle() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    } BBattle public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        } solve {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        } int a = in.nextInt(); a in.nextInt() in.nextInt in int b = in.nextInt(); b in.nextInt() in.nextInt in int c = in.nextInt(); c in.nextInt() in.nextInt in int d = in.nextInt(); d in.nextInt() in.nextInt in int sum1 = (a % d == 0 ? a / d : a / d + 1); sum1 (a % d == 0 ? a / d : a / d + 1) a % d == 0 a % d a d 0 a / d a d a / d + 1 a / d a d 1 int sum2 = (c % b == 0 ? c / b : c / b + 1); sum2 (c % b == 0 ? c / b : c / b + 1) c % b == 0 c % b c b 0 c / b c b c / b + 1 c / b c b 1 if (sum1 >= sum2) out.println("Yes");
            else out.println("No"); sum1 >= sum2 sum1 sum2 out.println("Yes") out.println out "Yes" out.println("No") out.println out "No" int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    }

    static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    }

    static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Tarek
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BBattle solver = new BBattle();
        solver.solve(1, in, out);
        out.close();
    }

    static class BBattle {
        public void solve(int testNumber, InputReader in, PrintWriter out) {

            int a = in.nextInt();
            int b = in.nextInt();
            int c = in.nextInt();
            int d = in.nextInt();
            int sum1 = (a % d == 0 ? a / d : a / d + 1);
            int sum2 = (c % b == 0 ? c / b : c / b + 1);
            // out.println(sum1);
            if (sum1 >= sum2) out.println("Yes");
            else out.println("No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}

