import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int P = scanner.nextInt();
        int Q = scanner.nextInt();
        int N = scanner.nextInt();
        double res = 0.0;
        int p1 = 0;
        // E(X + Y) = E(X) + E(Y)
        // Getting the ith item is independent!
        for (int i = 0; i < N; i++) {
            if (8 <= i) p1 = 0;
            else p1 = P / (int) Math.pow(2, i);
            double p2 = 1.0;
            for (int j = 1; j <= 100; j++) {
                res += p1 / 100.0 * p2 * j;
                if (p1 == 100) break;
                p2 *= 1.0 - p1 / 100.0;
                p1 = p1 + Q > 100 ? 100 : p1 + Q;
            }
        }
        System.out.printf("%.2f", res);
        scanner.close();
    }
}