#include <bits/stdc++.h>
using namespace std;

const double eps = 1e-3;
int w0, w, m;

bool check(double mid) {
    double g = 0;
    for (int i = 1; i <= m; i++) g += 1.0 * w / pow(mid / 100.0 + 1.0, i);
    cout << mid << ' ' << g << '\n';
    return g - w0 >= eps;
}

int main() {
    ios::sync_with_stdio(false);

    cin >> w0 >> w >> m;

    double l = 0, r = 300;
    double ans = -1;
    while (r - l >= eps) {
        double mid = l + (r - l) / 2;

        if (check(mid)) l = mid, ans = mid;
        else r = mid;
    }
    cout << fixed << setprecision(1) << ans << endl;

    return 0;
}