import java.util.*;
import java.math.BigInteger;
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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  }
} import java.util.*; util.* java import java.math.BigInteger; BigInteger java.math 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  }
} 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  } 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  } 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    } true {
      c -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    } c -= b c b if (c <= 0) {
        System.out.println("Yes");
        break;
      } c <= 0 c 0 {
        System.out.println("Yes");
        break;
      } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; a -= d a d if (a <= 0) {
        System.out.println("No");
        break;
      } a <= 0 a 0 {
        System.out.println("No");
        break;
      } System.out.println("No") System.out.println System.out System System.out "No" break; 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  }
} 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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  }
} Main
import java.util.*;
import java.math.BigInteger;
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 -= b;
      if (c <= 0) {
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0) {
        System.out.println("No");
        break;
      }
    }
  }
}
