import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            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 int T = 0; T 0 int K = 0; K 0 for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        } ; {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        } {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        } if(C<=0)
            {
                T++;
                break;
            } C<=0 C 0 {
                T++;
                break;
            } T++ T break; if(A<=0)
            {
                K++;
                break;
            } A<=0 A 0 {
                K++;
                break;
            } K++ K break; A = A - D A A - D A D K++ K C = C - B C C - B C B T++ T if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        } T>K T K {
            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 Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        int T = 0;
        int K = 0;
        for(;;)
        {
            if(C<=0)
            {
                T++;
                break;
            }
            if(A<=0)
            {
                K++;
                break;
            }
            A = A - D;
            K++;
            C = C - B;
            T++;
        }
        if(T>K)
        {
            System.out.println("Yes");
        }
        else
        {
            System.out.println("No");
        }
    }
}