import java.util.*;

public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	}
} import java.util.*; util.* java public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	}
} Main public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	} main {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	} Scanner keyboard = new Scanner(System.in); keyboard new Scanner(System.in) int A= keyboard.nextInt(); A keyboard.nextInt() keyboard.nextInt keyboard int B= keyboard.nextInt(); B keyboard.nextInt() keyboard.nextInt keyboard int C= keyboard.nextInt(); C keyboard.nextInt() keyboard.nextInt keyboard int D= keyboard.nextInt(); D keyboard.nextInt() keyboard.nextInt keyboard String ans = "No"; ans "No" int countT = 0; countT 0 int countA = 0; countA 0 while(A>0) {
			A -= D;
			countT++;
		} A>0 A 0 {
			A -= D;
			countT++;
		} A -= D A D countT++ countT while(C>0) {
			C -= B;
			countA++;
		} C>0 C 0 {
			C -= B;
			countA++;
		} C -= B C B countA++ countA if(countT >= countA) {
			ans = "Yes";
		} countT >= countA countT countA {
			ans = "Yes";
		} ans = "Yes" ans "Yes" System.out.println(ans) System.out.println System.out System System.out ans keyboard.close() keyboard.close keyboard String[] args args public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	}
} public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	}
} Main
import java.util.*;

public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int A= keyboard.nextInt();
		int B= keyboard.nextInt();
		int C= keyboard.nextInt();
		int D= keyboard.nextInt();
		
		String ans = "No";
		int countT = 0;
		int countA = 0;
		
		while(A>0) {
			A -= D;
			countT++;
		}
		while(C>0) {
			C -= B;
			countA++;
		}
		
		if(countT >= countA) {
			ans = "Yes";
		}
		
		
		System.out.println(ans);
		keyboard.close();	
		
	}
}
