import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    }
    
    
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    }
    
    
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    } 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 sw =0; sw 0 while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        } A>0 &&C>0 A>0 A 0 C>0 C 0 {
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        } if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            } sw==0&&C>=0 sw==0 sw 0 C>=0 C 0 {
                C=C-B;
                sw =1;
            } C=C-B C C-B C B sw =1 sw 1 if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            } sw==1&&A>=0 sw==1 sw 1 A>=0 A 0 {
                A = A-D;
                sw =0;
            } A = A-D A A-D A D sw =0 sw 0 if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        } A<=0 A 0 {
            System.out.println("No");
        } System.out.println("No") System.out.println System.out System System.out "No" {
            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 sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    }
    
    
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    }
    
    
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        
        int A =sc.nextInt();
        int B =sc.nextInt();
        int C =sc.nextInt();
        int D =sc.nextInt();
        
        
        
        int sw =0;
        
        while(A>0 &&C>0){
            
            if(sw==0&&C>=0){
                C=C-B;
                sw =1;
            }else if(sw==1&&A>=0){
                A = A-D;
                sw =0;
            }
            
        }
        
        if(A<=0){
            System.out.println("No");
        }else{
            System.out.println("Yes");
        }
        
        
    }
    
    
}
