import java.util.*;
public class Main {
	public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    }
}

 import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    }
} Main public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    } main {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A_hp = sc.nextLong(); A_hp sc.nextLong() sc.nextLong sc long B_at = sc.nextLong(); B_at sc.nextLong() sc.nextLong sc long C_hp = sc.nextLong(); C_hp sc.nextLong() sc.nextLong sc long D_at = sc.nextLong(); D_at sc.nextLong() sc.nextLong sc String ans = "Yes"; ans "Yes" while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		} (A_hp>0)&(C_hp>0) (A_hp>0) A_hp 0 (C_hp>0) C_hp 0 {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		} C_hp=C_hp-B_at C_hp C_hp-B_at C_hp B_at if (C_hp>0) {
				A_hp=A_hp-D_at;	
			} C_hp>0 C_hp 0 {
				A_hp=A_hp-D_at;	
			} A_hp=A_hp-D_at A_hp A_hp-D_at A_hp D_at if (A_hp<=0) {
			ans="No";
		} A_hp<=0 A_hp 0 {
			ans="No";
		} ans="No" ans "No" 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 sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    }
} public class Main {
	public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    }
} Main
import java.util.*;
public class Main {
	public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
		long A_hp = sc.nextLong();
		long B_at = sc.nextLong();
		long C_hp = sc.nextLong();
		long D_at = sc.nextLong();
		String ans = "Yes";
		
		while ((A_hp>0)&(C_hp>0)) {
			C_hp=C_hp-B_at;
			if (C_hp>0) {
				A_hp=A_hp-D_at;	
			}
		}

		if (A_hp<=0) {
			ans="No";
		}
		System.out.println(ans);
		//System.out.print(ans);
		

    }
}


