import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    }
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    } main {
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    } 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 int AoCount =0; AoCount 0 while(c > 0){
          c -= b; 
          AoCount ++; 
        } c > 0 c 0 {
          c -= b; 
          AoCount ++; 
        } c -= b c b AoCount ++ AoCount int TkCount =0; TkCount 0 while(a > 0){
          a -= d; 
          TkCount ++; 
        } a > 0 a 0 {
          a -= d; 
          TkCount ++; 
        } a -= d a d TkCount ++ TkCount if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      } TkCount<AoCount TkCount AoCount {
        System.out.println("No");
      } System.out.println("No") System.out.println System.out System System.out "No" {
        System.out.println("Yes");
      } System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    }
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    }
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	//数値の入力
		int a = sc.nextInt();
      	int b = sc.nextInt();
      	int c = sc.nextInt();
      	int d = sc.nextInt();
      	
      	//高橋が青木に攻撃
      	int AoCount =0;
      	while(c > 0){
          c -= b; 
          AoCount ++; 
        }
      	
      	//青木が高橋に攻撃
      	int TkCount =0;
      	while(a > 0){
          a -= d; 
          TkCount ++; 
        }

      	if(TkCount<AoCount){
        System.out.println("No");
      }else{
        System.out.println("Yes");
      }
    }
}