import java.util.*;
class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt(),b = sc.nextInt(),c = sc.nextInt(),d = sc.nextInt();
    int x = a/d+aa(a%d),y = c/b+aa(c%b);
    if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    }
  }

  public static int aa(int n){
    if(n>0){return 1;}
    return 0;
  }

  public static void pr(String str){
    System.out.print(str);
  }
  public static void pl(String str){
    System.out.println(str);
  }
} import java.util.*; util.* java class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt(),b = sc.nextInt(),c = sc.nextInt(),d = sc.nextInt();
    int x = a/d+aa(a%d),y = c/b+aa(c%b);
    if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    }
  }

  public static int aa(int n){
    if(n>0){return 1;}
    return 0;
  }

  public static void pr(String str){
    System.out.print(str);
  }
  public static void pl(String str){
    System.out.println(str);
  }
} Main public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt(),b = sc.nextInt(),c = sc.nextInt(),d = sc.nextInt();
    int x = a/d+aa(a%d),y = c/b+aa(c%b);
    if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt(),b = sc.nextInt(),c = sc.nextInt(),d = sc.nextInt();
    int x = a/d+aa(a%d),y = c/b+aa(c%b);
    if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt() a sc.nextInt() sc.nextInt sc b = sc.nextInt() b sc.nextInt() sc.nextInt sc c = sc.nextInt() c sc.nextInt() sc.nextInt sc d = sc.nextInt(); d sc.nextInt() sc.nextInt sc int x = a/d+aa(a%d) x a/d+aa(a%d) a/d a d aa(a%d) aa a%d a d y = c/b+aa(c%b); y c/b+aa(c%b) c/b c b aa(c%b) aa c%b c b if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    } x>=y x y {
      pl("Yes");
    } pl("Yes") pl "Yes" {
      pl("No");
    } pl("No") pl "No" String args[] args public static int aa(int n){
    if(n>0){return 1;}
    return 0;
  } aa {
    if(n>0){return 1;}
    return 0;
  } if(n>0){return 1;} n>0 n 0 {return 1;} return 1; 1 return 0; 0 int n n public static void pr(String str){
    System.out.print(str);
  } pr {
    System.out.print(str);
  } System.out.print(str) System.out.print System.out System System.out str String str str public static void pl(String str){
    System.out.println(str);
  } pl {
    System.out.println(str);
  } System.out.println(str) System.out.println System.out System System.out str String str str
import java.util.*;
class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt(),b = sc.nextInt(),c = sc.nextInt(),d = sc.nextInt();
    int x = a/d+aa(a%d),y = c/b+aa(c%b);
    if(x>=y){
      pl("Yes");
    }else{
      pl("No");
    }
  }

  public static int aa(int n){
    if(n>0){return 1;}
    return 0;
  }

  public static void pr(String str){
    System.out.print(str);
  }
  public static void pl(String str){
    System.out.println(str);
  }
}
