import java.util.*;
 
public class Main {
    public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    }
} Main public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    } main {
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    } Scanner scn = new Scanner(System.in); scn new Scanner(System.in) int A = scn.nextInt(); A scn.nextInt() scn.nextInt scn int B = scn.nextInt(); B scn.nextInt() scn.nextInt scn int C = scn.nextInt(); C scn.nextInt() scn.nextInt scn int D = scn.nextInt(); D scn.nextInt() scn.nextInt scn while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        } C>0 && A>0 C>0 C 0 A>0 A 0 {
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        } C = C-B C C-B C B if(C<=0){
                break;
            } C<=0 C 0 {
                break;
            } break; A = A-D A A-D A D if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        } C<=0 C 0 {
                System.out.println("Yes");
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" if(A<=0){    
               System.out.println("No");
        } A<=0 A 0 {    
               System.out.println("No");
        } 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 scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    }
} public class Main {
    public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    }
} Main
import java.util.*;
 
public class Main {
    public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int A = scn.nextInt();
        int B = scn.nextInt();
        int C = scn.nextInt();
        int D = scn.nextInt();
        
        while(C>0 && A>0){
            C = C-B;
            
            if(C<=0){
                break;
            }
            
            A = A-D;
        }    
          
        if(C<=0){
                System.out.println("Yes");
            }
        else if(A<=0){    
               System.out.println("No");
        }
    }
}