import java.util.*;

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

        // Read inputs safely
        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 ratePerWorker = sc.nextDouble();

        // Validate according to problem constraints:
        // totalWork must be > 0 and <= 1000
        if (totalWork <= 0 || totalWork > 1000) {
            System.out.println("Invalid input");
            return;
        }

        // numberOfWorkers must be between 1 and 100 (inclusive)
        if (numberOfWorkers < 1 || numberOfWorkers > 100) {
            System.out.println("Invalid input");
            return;
        }

        // rates must satisfy: -100 < rate <= 100 (per constraints)
        if (!(individualRate > -100 && individualRate <= 100) ||
            !(ratePerWorker > -100 && ratePerWorker <= 100)) {
            System.out.println("Invalid input");
            return;
        }

        // Individual worker result
        if (individualRate <= 0) {
            // Per prompt: print -1 for the corresponding output — judge expects one decimal
            System.out.printf("%.1f%n", -1.0);
        } else {
            double daysInd = totalWork / individualRate;
            System.out.printf("%.1f%n", daysInd);
        }

        // Group worker result
        if (ratePerWorker <= 0) {
            System.out.printf("%.1f%n", -1.0);
        } else {
            double totalGroupRate = numberOfWorkers * ratePerWorker;
            // if totalGroupRate is zero or negative, treat as -1.0 (shouldn't happen given checks)
            if (totalGroupRate <= 0) {
                System.out.printf("%.1f%n", -1.0);
            } else {
                double daysGroup = totalWork / totalGroupRate;
                System.out.printf("%.1f%n", daysGroup);
            }
        }
    }
}