import 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  } 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 String ans = "No"; ans "No" for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    } int i = 0; int i = 0; i 0 i < 200 i 200 i++ i++ i {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    } {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    } if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      } (i % 2) == 0 (i % 2) i 2 0 {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } c -= b c b if(c <= 0) {
          ans = "Yes";
          break;
        } c <= 0 c 0 {
          ans = "Yes";
          break;
        } ans = "Yes" ans "Yes" break; {
        a -= d;
        if(a <= 0) break;
      } a -= d a d if(a <= 0) break; a <= 0 a 0 break; System.out.println(ans) System.out.println System.out System System.out ans 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  }
} Main
import 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();
    String ans = "No";
    for(int i = 0; i < 200; i++) {
      if((i % 2) == 0) {
        c -= b;
        if(c <= 0) {
          ans = "Yes";
          break;
        }
      } else {
        a -= d;
        if(a <= 0) break;
      }
    }
    System.out.println(ans);
  }
}