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();
    String S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  }
} 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();
    String S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  }
} 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 S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  } main {
    Scanner sc = new Scanner(System.in);
    int A = sc.nextInt();
    int B = sc.nextInt();
    int C = sc.nextInt();
    int D = sc.nextInt();
    String S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  } 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 S = ""; S "" for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    } int i=0; int i=0; i 0 i<100 i 100 i++ i++ i {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    } {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    } C -= B C B A -= D A D if(C<=0) {
        S = "Yes";
        break;
      } C<=0 C 0 {
        S = "Yes";
        break;
      } S = "Yes" S "Yes" break; if(A<=0) {
        S = "No";
        break;
      } A<=0 A 0 {
        S = "No";
        break;
      } S = "No" S "No" break; System.out.println(S) System.out.println System.out System System.out S 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 S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  }
} 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 S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  }
} 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();
    String S = "";
    for(int i=0; i<100; i++) {
      C -= B;
      A -= D;
      if(C<=0) {
        S = "Yes";
        break;
      }
      if(A<=0) {
        S = "No";
        break;
      }
    }
        System.out.println(S);
  }
}