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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  }
} 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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  }
} 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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    int A = sc.nextInt();
    int B = sc.nextInt();
    int C = sc.nextInt();
    int D = sc.nextInt();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  } 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 int win =0 win 0 lose =0; lose 0 while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    } true {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    } C -= B C B if (C <= 0) {
        win++;
        break;
      } C <= 0 C 0 {
        win++;
        break;
      } win++ win break; A -= D A D if (A <= 0) {
        break;
      } A <= 0 A 0 {
        break;
      } break; if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    } win != 0 win 0 {
      System.out.println("Yes");
    } System.out.println("Yes") System.out.println System.out System System.out "Yes" {
      System.out.println("No");
    } System.out.println("No") System.out.println System.out System System.out "No" 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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  }
} 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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  }
} 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();
    int win =0, lose =0;
    while (true) {
      C -= B;
      if (C <= 0) {
        win++;
        break;
      }
      A -= D;
      if (A <= 0) {
        break;
      }
    }
    if (win != 0) {
      System.out.println("Yes");
    } else {
      System.out.println("No");
    }
  }
}