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