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();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		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){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		if(a<=0){
    		System.out.println("No");
		}else{
		    System.out.println("Yes");
		}
	}
} 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();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		if(a<=0){
    		System.out.println("No");
		}else{
		    System.out.println("Yes");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		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 i=0; i 0 while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		} a>0 && c>0 a>0 a 0 c>0 c 0 {
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		} if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    } i%2==0 i%2 i 2 0 {
		        c = c-b;
		    } c = c-b c c-b c b {
		        a = a-d;
		    } a = a-d a a-d a d i++ i 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){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		if(a<=0){
    		System.out.println("No");
		}else{
		    System.out.println("Yes");
		}
	}
} 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();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		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){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		int i=0;
		
		while(a>0 && c>0){
		    if(i%2==0){
		        c = c-b;
		    }else{
		        a = a-d;
		    }
		    i++;
		}
		
		if(a<=0){
    		System.out.println("No");
		}else{
		    System.out.println("Yes");
		}
	}
}
