#include <algorithm>
#include <iomanip>
#include <ios>
#include <iostream>
#include <utility>
#include <vector>

auto solve() {

    auto c = 0;
    auto p = 0.0;
    auto r = 0;

    std::cin >> r >> c >> p;

    auto dp = std::vector<double>(c);

    for (auto i = 0; i < c; ++i) {
        dp[i] = (p / 4) * (c - i - 1);
    }

    for (auto i = r - 2; i >= 0; --i) {
        auto new_dp = std::vector<double>(c);
        new_dp[c - 1] = (p / 4) * (r - i - 1);
        for (auto j = c - 2; j >= 0; --j) {
            const auto [mn, mx] = std::minmax(new_dp[j + 1], dp[j]);
            const auto diff = mx - mn;
            if (diff > p) {
                new_dp[j] = mn / 2 + mx / 2;
                continue;
            }
            const auto prob = diff / p;
            new_dp[j] = mn / 2 + (mn + diff / 2) * prob / 2 + mx * (1 - prob) / 2;
        }
        dp = std::move(new_dp);
    }

    std::cout << dp[0] << '\n';

}

auto main() -> int {

    std::cin.tie(nullptr);

    std::ios_base::sync_with_stdio(false);

    std::cout << std::fixed << std::setprecision(8);

    solve();

    return 0;

}