import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    }
    

        
} import java.util.*; util.* java import java.io.*; io.* java public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    }
    

        
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    } main {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    } Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in))); in new Scanner(new BufferedReader(new InputStreamReader(System.in))) int T_health = in.nextInt(); T_health in.nextInt() in.nextInt in int T_streng = in.nextInt(); T_streng in.nextInt() in.nextInt in int A_health = in.nextInt(); A_health in.nextInt() in.nextInt in int A_streng = in.nextInt(); A_streng in.nextInt() in.nextInt in int k = 0; k 0 while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        } A_health > 0 && T_health > 0 A_health > 0 A_health 0 T_health > 0 T_health 0 {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        } if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            } 1-k == 1 1-k 1 k 1 {
                k = 1;
                A_health =  A_health - T_streng;
            } k = 1 k 1 A_health =  A_health - T_streng A_health A_health - T_streng A_health T_streng {
                k = 0;
                T_health = T_health - A_streng;
            } k = 0 k 0 T_health = T_health - A_streng T_health T_health - A_streng T_health A_streng if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            } T_health <= 0 T_health 0 {
                System.out.println("No");
            } System.out.println("No") System.out.println System.out System System.out "No" if(A_health <= 0) {
                System.out.println("Yes");
            } A_health <= 0 A_health 0 {
                System.out.println("Yes");
            } 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) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    }
    

        
} public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    }
    

        
} Main
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        int T_health = in.nextInt();
        int T_streng = in.nextInt();
        int A_health = in.nextInt();
        int A_streng = in.nextInt();
     
        int k = 0;
        while(A_health > 0 && T_health > 0) {
            
            if(1-k == 1) {
                k = 1;
                A_health =  A_health - T_streng;
            }
            else {
                k = 0;
                T_health = T_health - A_streng;
            }
            
            if(T_health <= 0) {
                System.out.println("No");
            }
            else if(A_health <= 0) {
                System.out.println("Yes");
            }
        }
    }
    

        
}
