import java.io.IOException;
import java.io.PrintStream;
import java.util.Scanner;

public class Main {
	static PrintStream o = System.out;
	
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	}
} import java.io.IOException; IOException java.io import java.io.PrintStream; PrintStream java.io import java.util.Scanner; Scanner java.util public class Main {
	static PrintStream o = System.out;
	
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	}
} Main static PrintStream o = System.out; o System.out System System.out public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	} main {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) short thealth = sc.nextShort(); thealth sc.nextShort() sc.nextShort sc short tattack = sc.nextShort(); tattack sc.nextShort() sc.nextShort sc short ahealth = sc.nextShort(); ahealth sc.nextShort() sc.nextShort sc short aattack = sc.nextShort(); aattack sc.nextShort() sc.nextShort sc while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		} true {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		} ahealth -= tattack ahealth tattack if (ahealth <= 0) {
				o.println("Yes");
				break;
			} ahealth <= 0 ahealth 0 {
				o.println("Yes");
				break;
			} o.println("Yes") o.println o "Yes" break; thealth -= aattack thealth aattack if (thealth <= 0) {
				o.println("No");
				break;
			} thealth <= 0 thealth 0 {
				o.println("No");
				break;
			} o.println("No") o.println o "No" break; String[] args args public class Main {
	static PrintStream o = System.out;
	
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	}
} public class Main {
	static PrintStream o = System.out;
	
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	}
} Main
import java.io.IOException;
import java.io.PrintStream;
import java.util.Scanner;

public class Main {
	static PrintStream o = System.out;
	
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		short thealth = sc.nextShort();
		short tattack = sc.nextShort();
		short ahealth = sc.nextShort();
		short aattack = sc.nextShort();
		while (true) {
			ahealth -= tattack;
			if (ahealth <= 0) {
				o.println("Yes");
				break;
			}
			thealth -= aattack;
			if (thealth <= 0) {
				o.println("No");
				break;
			}
		}
	}
}