import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    }
} Main public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    } main {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("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 = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      } true {
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      } C = C-B C C-B C B A = A-D A A-D A D if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        } C<=0 C 0 {
          System.out.print("Yes"); 
        break;
      } System.out.print("Yes") System.out.print System.out System System.out "Yes" break; if(A<=0){
          System.out.print("No");
         break;
        } A<=0 A 0 {
          System.out.print("No");
         break;
        } System.out.print("No") System.out.print 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();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    }
} public class Main {
    public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
      
      int A = sc.nextInt();//高HP
      int B = sc.nextInt();//高攻撃力
      int C = sc.nextInt();//青HP
      int D = sc.nextInt();//青攻撃力
      
      //どちらかが先にHP０になるまで
      while(true){
       C = C-B;
       A = A-D;
      
      if(C<=0){
          System.out.print("Yes"); 
        break;
      }
        else if(A<=0){
          System.out.print("No");
         break;
        }
      }
    }
}