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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    }
} 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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    }
} 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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    } main {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    } 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 boolean flag = true; flag true while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        } flag {
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        } C=C-B C C-B C B A=A-D A A-D A D if(C<=0 || A<=0){
                flag = false;
            } C<=0 || A<=0 C<=0 C 0 A<=0 A 0 {
                flag = false;
            } flag = false flag false if(C<=0) System.out.println("Yes");
        else System.out.println("No"); C<=0 C 0 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" 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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    }
} 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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    }
} 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();
        boolean flag = true;
        while(flag){
            C=C-B;
            A=A-D;
            if(C<=0 || A<=0){
                flag = false;
            }
        }
        if(C<=0) System.out.println("Yes");
        else System.out.println("No");
    }
}