import java.util.Scanner;
//import java.util.Arrays;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int tHp = sc.nextInt(); tHp sc.nextInt() sc.nextInt sc int tAttack = sc.nextInt(); tAttack sc.nextInt() sc.nextInt sc int aHp = sc.nextInt(); aHp sc.nextInt() sc.nextInt sc int aAttack = sc.nextInt(); aAttack sc.nextInt() sc.nextInt sc String result = ""; result "" while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		} true {
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		} aHp -= tAttack aHp tAttack if(aHp <= 0){
				result = "Yes";
				break;
			} aHp <= 0 aHp 0 {
				result = "Yes";
				break;
			} result = "Yes" result "Yes" break; tHp -= aAttack tHp aAttack if(tHp <= 0){
				result = "No";
				break;
			} tHp <= 0 tHp 0 {
				result = "No";
				break;
			} result = "No" result "No" break; System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	}
} Main
import java.util.Scanner;
//import java.util.Arrays;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int tHp = sc.nextInt();
		int tAttack = sc.nextInt();
		int aHp = sc.nextInt();
		int aAttack = sc.nextInt();
		String result = "";
		while(true){
			aHp -= tAttack;
			if(aHp <= 0){
				result = "Yes";
				break;
			}
			tHp -= aAttack;
			if(tHp <= 0){
				result = "No";
				break;
			}
		}
		System.out.println(result);
	}
}
