import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    }

} import java.io.FileNotFoundException; FileNotFoundException java.io import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    }

} Main public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    } main {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=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 boolean flag = true; flag true while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	} flag {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	} C -= B C B if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		} B<=0 B 0 {
    			flag = false;
    		} flag = false flag false {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		} A -= D A D if(A<=0) {
        			flag = false;
        		} A<=0 A 0 {
        			flag = false;
        		} flag = false flag false if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	} C<=0 C 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) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    }

} public class Main {
    public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    }

} Main
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	int A = sc.nextInt();
    	int B = sc.nextInt();
    	int C = sc.nextInt();
    	int D = sc.nextInt();

    	boolean flag = true;

    	while(flag) {
    		C -= B;
    		if(B<=0) {
    			flag = false;
    		} else {
        		A -= D;
        		if(A<=0) {
        			flag = false;
        		}
    		}
    	}
    	if(C<=0) {
    		System.out.println("Yes");
    	} else {
    		System.out.println("No");
    	}
    }

}