import java.util.Scanner;
public class Main {
     public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     }
    
} import java.util.Scanner; Scanner java.util public class Main {
     public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     }
    
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     } main {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     } 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 for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        } int i = 0; int i = 0; i 0 i < 100 i 100 i++ i++ i {
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        } {
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        } C = C - B C C - B C B if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            } C <= 0 C 0 {
                System.out.println("Yes");
                i = 101;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" i = 101 i 101 {
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            } A = A - D A A - D A D if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                } A <= 0 A 0 {
                    System.out.println("No");
                    i = 101;
                } System.out.println("No") System.out.println System.out System System.out "No" i = 101 i 101 {
                    //なし
                } String[] args args public class Main {
     public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     }
    
} public class Main {
     public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     }
    
} Main
import java.util.Scanner;
public class Main {
     public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        for(int i = 0; i < 100; i++){
            C = C - B;
            if(C <= 0){
                System.out.println("Yes");
                i = 101;
            }else{
                A = A - D;
                if(A <= 0){
                    System.out.println("No");
                    i = 101;
                }else{
                    //なし
                }
            }
        }
     }
    
}