import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	}
} Main public static void main(String[] args) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	} main {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	} int a a b b c c d; d Scanner scan = new Scanner(System.in); scan new Scanner(System.in) a = scan.nextInt() a scan.nextInt() scan.nextInt scan b = scan.nextInt() b scan.nextInt() scan.nextInt scan c = scan.nextInt() c scan.nextInt() scan.nextInt scan d = scan.nextInt() d scan.nextInt() scan.nextInt scan int count = 0; count 0 while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		} a > 0 && c > 0 a > 0 a 0 c > 0 c 0 {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		} count++ count if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			} count % 2 != 0 count % 2 count 2 0 {
				c -= b;
			} c -= b c b {
				a -= d;
			} a -= d a d if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			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" if(c <= 0) {
			System.out.println("Yes");
		} c <= 0 c 0 {
			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) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	}
} public class Main {
	public static void main(String[] args) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int a, b, c, d;
		Scanner scan = new Scanner(System.in);

		a = scan.nextInt();
		b = scan.nextInt();
		c = scan.nextInt();
		d = scan.nextInt();

		int count = 0;
		while(a > 0 && c > 0) {
			count++;
			if(count % 2 != 0) {
				c -= b;
			} else {
				a -= d;
			}
		}

		if(a <= 0) {
			System.out.println("No");
		} else if(c <= 0) {
			System.out.println("Yes");
		}
	}
}
