import java.util.*;

class Main{
    public static void main(String[] args){
        // 入力受付
        Scanner sc = new Scanner(System.in);    //scanner
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        // バトル
        while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        }
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] args){
        // 入力受付
        Scanner sc = new Scanner(System.in);    //scanner
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        // バトル
        while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        }
    }
} Main public static void main(String[] args){
        // 入力受付
        Scanner sc = new Scanner(System.in);    //scanner
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        // バトル
        while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        }
    } main {
        // 入力受付
        Scanner sc = new Scanner(System.in);    //scanner
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        // バトル
        while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        }
    } 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 while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        } true {
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        } 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; 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; String[] args args
import java.util.*;

class Main{
    public static void main(String[] args){
        // 入力受付
        Scanner sc = new Scanner(System.in);    //scanner
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        // バトル
        while(true){
            // 高橋くんの攻撃
            C-=B;
            if(C<=0){
                System.out.println("Yes");
                break;
            }
            // 青木くんの攻撃
            A-=D;
            if(A<=0){
                System.out.println("No");
                break;
            }
        }
    }
}
