import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

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

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    } main {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    } 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 (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        } true {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        } C = C - B C 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 = A - D A 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) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        while (true) {
            
            C = C - B;
            if (C <= 0) {
            	System.out.println("Yes");
            	return;
            }
          
            A = A - D;
            if (A <= 0) {
                System.out.println("No");
                return;
            }
        }

    }
}
