import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    }
} Main public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    } main {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    } try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        } {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc int C = sc.nextInt(); C sc.nextInt() sc.nextInt sc int D = sc.nextInt(); D sc.nextInt() sc.nextInt sc for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            } ; {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            } {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            } C -= B C B if (C <= 0) {
                    System.out.println("Yes");
                    return;
                } C <= 0 C 0 {
                    System.out.println("Yes");
                    return;
                } System.out.println("Yes") System.out.println System.out System System.out "Yes" return; A -= D A D if (A <= 0) {
                    System.out.println("No");
                    return;
                } A <= 0 A 0 {
                    System.out.println("No");
                    return;
                } System.out.println("No") System.out.println System.out System System.out "No" return; String[] args args public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    }
} public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();

            for (;;) {
                C -= B;
                if (C <= 0) {
                    System.out.println("Yes");
                    return;
                }
                A -= D;
                if (A <= 0) {
                    System.out.println("No");
                    return;
                }
            }
        }
    }
}
