import java.util.Scanner;

/**
 * Main
 */
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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} import java.util.Scanner; Scanner 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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} 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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    } main {
        Scanner sc = new Scanner(System.in);

        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        int restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    } 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 restT = A; restT A int restA = C; restA C while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        } restT > 0 && restA > 0 restT > 0 restT 0 restA > 0 restA 0 {
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        } restA -= B restA B if(restA <= 0){
                System.out.println("Yes");
                break;
            } restA <= 0 restA 0 {
                System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; restT -= D restT D if(restT <= 0){
                System.out.println("No");
                break;
            } restT <= 0 restT 0 {
                System.out.println("No");
                break;
            } System.out.println("No") System.out.println System.out System System.out "No" break; 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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} 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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} Main
import java.util.Scanner;

/**
 * Main
 */
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 restT = A;
        int restA = C;

        while(restT > 0 && restA > 0){
            restA -= B;
            if(restA <= 0){
                System.out.println("Yes");
                break;
            }
            restT -= D;
            if(restT <= 0){
                System.out.println("No");
                break;
            }
        }
    }
}
