
import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	}

} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	}

} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	} main {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	} Scanner cin = new Scanner(System.in); cin new Scanner(System.in) int A A B B C C D; D A = cin.nextInt() A cin.nextInt() cin.nextInt cin B = cin.nextInt() B cin.nextInt() cin.nextInt cin C = cin.nextInt() C cin.nextInt() cin.nextInt cin D = cin.nextInt() D cin.nextInt() cin.nextInt cin while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		} true {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		} C -= B C B if(C<=0) {
				System.out.println("Yes");
				return;
			} C<=0 C 0 {
				System.out.println("Yes");
				return;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" return; A -= D A D if(A<=0) {
				System.out.println("No");
				return;
			} A<=0 A 0 {
				System.out.println("No");
				return;
			} System.out.println("No") System.out.println System.out System System.out "No" return; String[] args args public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	}

} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	}

} Main

import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		
		int A,B,C,D;
		
		A = cin.nextInt();
		B = cin.nextInt();
		C = cin.nextInt();
		D = cin.nextInt();
		
		while(true) {
			
			C -= B;
			if(C<=0) {
				System.out.println("Yes");
				return;
			}
			A -= D;
			if(A<=0) {
				System.out.println("No");
				return;
			}
			
		}
		
		
	}

}
