import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int thp = sc.nextInt(); thp sc.nextInt() sc.nextInt sc int tk = sc.nextInt(); tk sc.nextInt() sc.nextInt sc int ahp = sc.nextInt(); ahp sc.nextInt() sc.nextInt sc int ak = sc.nextInt(); ak sc.nextInt() sc.nextInt sc String result = ""; result "" for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      } int i=0; int i=0; i 0 i<100 i 100 i++ i++ i {
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      } {
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      } ahp = ahp - tk ahp ahp - tk ahp tk if(ahp <= 0){
        result = "Yes";
        break;
       } ahp <= 0 ahp 0 {
        result = "Yes";
        break;
       } result = "Yes" result "Yes" break; thp = thp - ak thp thp - ak thp ak if(thp <= 0){
        result = "No";
        break;
      } thp <= 0 thp 0 {
        result = "No";
        break;
      } result = "No" result "No" break; System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int thp = sc.nextInt();
        int tk = sc.nextInt();
		int ahp = sc.nextInt();
        int ak = sc.nextInt();
      
            String result = "";
      
      for(int i=0; i<100; i++){
        ahp = ahp - tk;
        
       if(ahp <= 0){
        result = "Yes";
        break;
       }
              
      	thp = thp - ak;
      
      if(thp <= 0){
        result = "No";
        break;
      }
      
      }
		// 文字列の入力
		System.out.println(result);
	}
}