import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc int C = sc.nextInt(); C sc.nextInt() sc.nextInt sc int D = sc.nextInt(); D sc.nextInt() sc.nextInt sc while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		} A > 0 && C > 0 A > 0 A 0 C > 0 C 0 {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		} C -= B C B if(C<=0) {
				break;
			} C<=0 C 0 {
				break;
			} break; A -= D A D if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		} A <= 0 A 0 {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		while (A > 0 && C > 0) {
			C -= B;
			if(C<=0) {
				break;
			}
			A -= D;
		}
		if (A <= 0) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}
	}
}