import java.util.*;
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();
  boolean flag=true;
  while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  }
    
}
} import java.util.*; util.* java 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();
  boolean flag=true;
  while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  }
    
}
} 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();
  boolean flag=true;
  while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  }
    
} main {
  Scanner sc=new Scanner(System.in);
  int A=sc.nextInt();
  int B=sc.nextInt();
  int C=sc.nextInt();
  int D=sc.nextInt();
  boolean flag=true;
  while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  }
    
} 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 boolean flag=true; flag true while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  } flag {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  } if(A>0)
        C=C-B; A>0 A 0 C=C-B C C-B C B if(D>0)
        A=A-D; D>0 D 0 A=A-D A A-D A D if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    } C<=0 C 0 {
       System.out.println("Yes");
       flag=false;
   } System.out.println("Yes") System.out.println System.out System System.out "Yes" flag=false flag false if(A<=0)
    {
        System.out.println("No");
        flag=false;
    } A<=0 A 0 {
        System.out.println("No");
        flag=false;
    } System.out.println("No") System.out.println System.out System System.out "No" flag=false flag false String [] args args
import java.util.*;
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();
  boolean flag=true;
  while(flag)
  {
        if(A>0)
        C=C-B;
        if(D>0)
        A=A-D;
    
   if(C<=0)
   {
       System.out.println("Yes");
       flag=false;
   }
    else if(A<=0)
    {
        System.out.println("No");
        flag=false;
    }
  }
    
}
}
