import java.util.*;

public class ProjectCompletion {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

       
        if (!sc.hasNextDouble()) {
            System.out.println("Invalid input");
            return;
        }
        double totalWork = sc.nextDouble();

        if (!sc.hasNextDouble()) {
            System.out.println("Invalid input");
            return;
        }
        double individualRate = sc.nextDouble();

        if (!sc.hasNextInt()) {
            System.out.println("Invalid input");
            return;
        }
        int numberOfWorkers = sc.nextInt();

        if (!sc.hasNextDouble()) {
            System.out.println("Invalid input");
            return;
        }
        double workRatePerWorker = sc.nextDouble();

        // Validate total work
        if (totalWork <= 0) {
            System.out.println("Invalid input");
            return;
        }

        // --- Individual Worker ---
        if (individualRate <= 0) {
            System.out.println("-1");
        } else {
            double daysInd = totalWork / individualRate;
            System.out.printf("%.1f%n", daysInd);  // ✅ new line
        }

        // --- Group Worker ---
        if (numberOfWorkers <= 0 || workRatePerWorker <= 0) {
            System.out.println("-1");
        } else {
            double groupRate = numberOfWorkers * workRatePerWorker;
            double daysGrp = totalWork / groupRate;
            System.out.printf("%.1f%n", daysGrp);  // ✅ new line
        }
    }
}