import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    } main {
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int healthA = sc.nextInt(); healthA sc.nextInt() sc.nextInt sc int attackB = sc.nextInt(); attackB sc.nextInt() sc.nextInt sc int healthC = sc.nextInt(); healthC sc.nextInt() sc.nextInt sc int attackD = sc.nextInt(); attackD sc.nextInt() sc.nextInt sc boolean isTakahashiWin; isTakahashiWin while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        } true {
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        } healthC -= attackB healthC attackB if(healthC <= 0){
                isTakahashiWin = true;
                break;
            } healthC <= 0 healthC 0 {
                isTakahashiWin = true;
                break;
            } isTakahashiWin = true isTakahashiWin true break; healthA -= attackD healthA attackD if(healthA <= 0){
                isTakahashiWin = false;
                break;
            } healthA <= 0 healthA 0 {
                isTakahashiWin = false;
                break;
            } isTakahashiWin = false isTakahashiWin false break; System.out.println(isTakahashiWin == true ? "Yes" : "No") System.out.println System.out System System.out isTakahashiWin == true ? "Yes" : "No" isTakahashiWin == true isTakahashiWin true "Yes" "No" String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int healthA = sc.nextInt();
        int attackB = sc.nextInt();
        int healthC = sc.nextInt();
        int attackD = sc.nextInt();
        
        boolean isTakahashiWin;
        while(true){
            healthC -= attackB;
            if(healthC <= 0){
                isTakahashiWin = true;
                break;
            }
            healthA -= attackD;
            if(healthA <= 0){
                isTakahashiWin = false;
                break;
            }
        }
        System.out.println(isTakahashiWin == true ? "Yes" : "No");
    }
}