import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    }

} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util public class Main {

    public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    }

} Main public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    } main {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    } InputStreamReader is = new InputStreamReader(System.in); is new InputStreamReader(System.in) BufferedReader reader = new BufferedReader(is); reader new BufferedReader(is) List<String> mylist = new ArrayList<>(); mylist new ArrayList<>() String strinput = reader.readLine(); strinput reader.readLine() reader.readLine reader while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        } strinput != null strinput null {

            mylist.add(strinput);
            strinput = reader.readLine();

        } mylist.add(strinput) mylist.add mylist strinput strinput = reader.readLine() strinput reader.readLine() reader.readLine reader String arr01[] = mylist.get(0).split(" "); arr01 mylist.get(0).split(" ") mylist.get(0).split mylist.get(0) mylist.get mylist 0 " " int a = Integer.valueOf(arr01[0]); a Integer.valueOf(arr01[0]) Integer.valueOf Integer arr01[0] arr01 0 int b = Integer.valueOf(arr01[1]); b Integer.valueOf(arr01[1]) Integer.valueOf Integer arr01[1] arr01 1 int c = Integer.valueOf(arr01[2]); c Integer.valueOf(arr01[2]) Integer.valueOf Integer arr01[2] arr01 2 int d = Integer.valueOf(arr01[3]); d Integer.valueOf(arr01[3]) Integer.valueOf Integer arr01[3] arr01 3 Boolean chkflg = true; chkflg true Boolean isT = true; isT true while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        } chkflg {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        } if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            } isT {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } 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; isT = false isT false {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            } 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; isT = true isT true String[] args args public class Main {

    public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    }

} public class Main {

    public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    }

} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) throws Exception {
        InputStreamReader is = new InputStreamReader(System.in);
        BufferedReader reader = new BufferedReader(is);

        List<String> mylist = new ArrayList<>();

        // 標準入力からの値を変数strinputに代入
        String strinput = reader.readLine();

        while (strinput != null) {

            mylist.add(strinput);
            strinput = reader.readLine();

        }

        String arr01[] = mylist.get(0).split(" ");

        int a = Integer.valueOf(arr01[0]);
        int b = Integer.valueOf(arr01[1]);
        int c = Integer.valueOf(arr01[2]);
        int d = Integer.valueOf(arr01[3]);

        Boolean chkflg = true;
        Boolean isT = true;

        while (chkflg) {
            if (isT) {
                c -= b;
                if (c <= 0) {
                    System.out.println("Yes");
                    break;
                }

                isT = false;
            } else {

                a -= d;
                if (a <= 0) {
                    System.out.println("No");
                    break;
                }

                isT = true;
            }
        }

    }

}
