import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  }
} Main public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  } main {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  } BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) String[] str = in.readLine().split(" "); str in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int a = Integer.parseInt(str[0]); a Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int b = Integer.parseInt(str[1]); b Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 int c = Integer.parseInt(str[2]); c Integer.parseInt(str[2]) Integer.parseInt Integer str[2] str 2 int d = Integer.parseInt(str[3]); d Integer.parseInt(str[3]) Integer.parseInt Integer str[3] str 3 boolean flg = true; flg true for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    } ; flg == true flg true {
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    } {
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    } c = c-b c c-b c b if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      } c<=0 c 0 {
        System.out.println("Yes");
        flg = false;
        break;
      } System.out.println("Yes") System.out.println System.out System System.out "Yes" flg = false flg false break; a = a-d a a-d a d if(a<=0){
        System.out.println("No");
        flg = false;
      } a<=0 a 0 {
        System.out.println("No");
        flg = false;
      } System.out.println("No") System.out.println System.out System System.out "No" flg = false flg false String[] args args public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  }
} public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    boolean flg = true;
    for(; flg == true;){
      c = c-b;
      if(c<=0){
        System.out.println("Yes");
        flg = false;
        break;
      }
      a = a-d;
      if(a<=0){
        System.out.println("No");
        flg = false;
      }
    }
  }
}