import java.util.*;

    public class Main {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();
            int Chp = C;
            int Ahp = A;
            while(Chp > 0){
                Chp -= B;

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

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

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

                if(Ahp <= 0){
                    System.out.println("No");
                    return;
                }
                Ahp -= D;
            }
            System.out.println("Yes");
        } Scanner sc = new Scanner(System.in); sc 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 int Chp = C; Chp C int Ahp = A; Ahp A while(Chp > 0){
                Chp -= B;

                if(Ahp <= 0){
                    System.out.println("No");
                    return;
                }
                Ahp -= D;
            } Chp > 0 Chp 0 {
                Chp -= B;

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

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

                if(Ahp <= 0){
                    System.out.println("No");
                    return;
                }
                Ahp -= D;
            }
            System.out.println("Yes");
        }
    } Main
import java.util.*;

    public class Main {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();
            int Chp = C;
            int Ahp = A;
            while(Chp > 0){
                Chp -= B;

                if(Ahp <= 0){
                    System.out.println("No");
                    return;
                }
                Ahp -= D;
            }
            System.out.println("Yes");
        }
    }
