import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    }
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    }
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    } main {
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int tA = scan.nextInt(); tA scan.nextInt() scan.nextInt scan int tB = scan.nextInt(); tB scan.nextInt() scan.nextInt scan int aC = scan.nextInt(); aC scan.nextInt() scan.nextInt scan int aD = scan.nextInt(); aD scan.nextInt() scan.nextInt scan String ans = "Yes"; ans "Yes" while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        } tA>0 && aC>0 tA>0 tA 0 aC>0 aC 0 {
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        } aC = aC - tB aC aC - tB aC tB if(aC <= 0){
            ans="Yes";
            break;
          } aC <= 0 aC 0 {
            ans="Yes";
            break;
          } ans="Yes" ans "Yes" break; tA = tA - aD tA tA - aD tA aD if(tA <= 0){
            ans = "No";
            break;
          } tA <= 0 tA 0 {
            ans = "No";
            break;
          } ans = "No" ans "No" break; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    }
} public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    }
} Main
import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int tA = scan.nextInt();
		int tB = scan.nextInt();
		int aC = scan.nextInt();
		int aD = scan.nextInt();
		String ans = "Yes";
		
		while(tA>0 && aC>0){
          //高橋君の攻撃
          aC = aC - tB;
          if(aC <= 0){
            ans="Yes";
            break;
          }

          //青木君の攻撃
          tA = tA - aD;
          if(tA <= 0){
            ans = "No";
            break;
          }
        }
      
        //回答表示
        System.out.println(ans);
    }
}