import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    }
} Main public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    } main {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    } Scanner stdIn= new Scanner(System.in); stdIn new Scanner(System.in) int a = stdIn.nextInt(); a stdIn.nextInt() stdIn.nextInt stdIn int b = stdIn.nextInt(); b stdIn.nextInt() stdIn.nextInt stdIn int c = stdIn.nextInt(); c stdIn.nextInt() stdIn.nextInt stdIn int d = stdIn.nextInt(); d stdIn.nextInt() stdIn.nextInt stdIn for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        } ; {
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        } {
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        } if(c<=b){
                System.out.println("Yes");
                break;
            } c<=b c b {
                System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; c=c-b c c-b c b if(a<=d){
                 System.out.println("No");
                break;
            } a<=d a d {
                 System.out.println("No");
                break;
            } System.out.println("No") System.out.println System.out System System.out "No" break; a=a-d a a-d a d String[] args args public class Main {
    public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
       Scanner stdIn= new Scanner(System.in);

        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        int c = stdIn.nextInt();
        int d = stdIn.nextInt();
        for(;;){
            if(c<=b){
                System.out.println("Yes");
                break;
            }
            c=c-b;
            if(a<=d){
                 System.out.println("No");
                break;
            }
            a=a-d;
        }
    }
}
