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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 0){
            	System.out.println("No");
              	break;
            }                     
        }
    }
} 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 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 while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 0){
            	System.out.println("No");
              	break;
            }                     
        } true {
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 0){
            	System.out.println("No");
              	break;
            }                     
        } c -= b c b if(c <= 0){
            	System.out.println("Yes");
              	break;
            } c <= 0 c 0 {
            	System.out.println("Yes");
              	break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; a -= d a d if(a <= 0){
            	System.out.println("No");
              	break;
            } a <= 0 a 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 0){
            	System.out.println("No");
              	break;
            }                     
        }
    }
} 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();
      
      	while(true){
        	c -= b;
          	if(c <= 0){
            	System.out.println("Yes");
              	break;
            }
            a -= d;
            if(a <= 0){
            	System.out.println("No");
              	break;
            }                     
        }
    }
}